I wanted to implement BarabasiAlbertGenerator to generate graph. After creating all Factory objects in main method and changing the Objects (V, E) to (Integer, String) in the generator class, two errors worried me after making all possible modification.
1. index_vertex.put(v, i); type mismatch
2. index_vertex.put(newVertex, new Integer(vertex_index.size() - 1));// an Object of Integer cannot be instantiated. I made several casting the errors still appear. Please any help on how to correct the errors.
public class BarabasiAlbertGenerator<Integer, String> implements EvolvingGraphGenerator<Integer, String> {
mGraph = graphFactory.create();
vertex_index = new ArrayList<Integer>(2*init_vertices);
index_vertex = new HashMap<Integer, Integer>(2*init_vertices);
for (int i = 0; i < init_vertices; i++) {
Integer v = vertexFactory.create();
mGraph.addVertex(v);
vertex_index.add(v);
index_vertex.put(v, i);
seedVertices.add(v);
}
mElapsedTimeSteps = 0;
}
for (Pair<Integer> pair : added_pairs)
{
Integer v1 = pair.getFirst();
Integer v2 = pair.getSecond();
if (mGraph.getDefaultEdgeType() != EdgeType.UNDIRECTED ||
!mGraph.isNeighbor(v1, v2))
mGraph.addEdge(edgeFactory.create(), pair);
}
// now that we're done attaching edges to this new vertex,
// add it to the index
vertex_index.add(newVertex);
index_vertex.put(newVertex, new Integer(vertex_index.size() - 1));
}
public static void main(String[] args) {
SparseGraph<Integer, String> sir = new SparseGraph<Integer, String>();
ConstantFactory<Graph<Integer, String>> graphFactory = new ConstantFactory<Graph<Integer, String>>(sir);
InstantiateFactory<Integer> vertexFactory = new InstantiateFactory<Integer>(Integer.class);
InstantiateFactory<String> edgeFactory = new InstantiateFactory<String>(String.class);
HashSet<Integer> seedVertices = new HashSet<Integer>();
int evolve = 1;
int node = 10;
int agents = 100;
BarabasiAlbertGenerator<Integer, String> bbr = new BarabasiAlbertGenerator<Integer, String>(graphFactory, vertexFactory, edgeFactory, agents, node, seedVertices);
bbr.evolveGraph(evolve);
Layout<Integer, String> layout = new CircleLayout(sir);
layout.setSize(new Dimension(300,300));
BasicVisualizationServer<Integer,String> vv =
new BasicVisualizationServer<Integer,String>(layout);
vv.setPreferredSize(new Dimension(350,350));
// Setup up a new vertex to paint transformer...
Transformer<Integer,Paint> vertexPaint = new Transformer<Integer,Paint>() {
public Paint transform(Integer i) {
return Color.GREEN;
}
};
// Set up a new stroke Transformer for the edges
float dash[] = {10.0f};
final Stroke edgeStroke = new BasicStroke(1.0f, BasicStroke.CAP_BUTT,
BasicStroke.JOIN_MITER, 10.0f, dash, 0.0f);
Transformer<String, Stroke> edgeStrokeTransformer =
new Transformer<String, Stroke>() {
public Stroke transform(String s) {
return edgeStroke;
}
};
vv.getRenderContext().setVertexFillPaintTransformer(vertexPaint);
vv.getRenderContext().setEdgeStrokeTransformer(edgeStrokeTransformer);
vv.getRenderContext().setVertexLabelTransformer(new ToStringLabeller());
//vv.getRenderContext().setEdgeLabelTransformer(new ToStringLabeller());
vv.getRenderer().getVertexLabelRenderer().setPosition(Position.CNTR);
JFrame frame = new JFrame("Undirected Graph ");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(vv);
frame.pack();
frame.setVisible(true);
}
I don't think you want to use InstantiateFactory.
I was able to run your program after changing it to look like this (mostly the vertex and edge factories):
public static void main(String[] args) {
SparseGraph<Integer, String> sir = new SparseGraph<Integer, String>();
ConstantFactory<Graph<Integer, String>> graphFactory = new ConstantFactory<Graph<Integer, String>>(sir);
Factory<Integer> vertexFactory = new Factory<Integer>() {
int i = 0;
public Integer create() {
return i++;
}
};
Factory<String> edgeFactory = new Factory<String>() {
int i = 0;
public String create() {
return "" + i++;
}
};
HashSet<Integer> seedVertices = new HashSet<Integer>();
int evolve = 1;
int node = 10;
int agents = 100;
BarabasiAlbertGenerator<Integer, String> bbr = new BarabasiAlbertGenerator<Integer, String>(graphFactory, vertexFactory, edgeFactory, agents, node, seedVertices);
bbr.evolveGraph(evolve);
Layout<Integer, String> layout = new CircleLayout(sir);
layout.setSize(new Dimension(300, 300));
BasicVisualizationServer<Integer, String> vv =
new BasicVisualizationServer<Integer, String>(layout);
vv.setPreferredSize(new Dimension(350, 350));
// Setup up a new vertex to paint transformer...
Transformer<Integer, Paint> vertexPaint = new Transformer<Integer, Paint>() {
public Paint transform(Integer i) {
return Color.GREEN;
}
};
// Set up a new stroke Transformer for the edges
float dash[] = {10.0f};
final Stroke edgeStroke = new BasicStroke(1.0f, BasicStroke.CAP_BUTT,
BasicStroke.JOIN_MITER, 10.0f, dash, 0.0f);
Transformer<String, Stroke> edgeStrokeTransformer =
new Transformer<String, Stroke>() {
public Stroke transform(String s) {
return edgeStroke;
}
};
vv.getRenderContext().setVertexFillPaintTransformer(vertexPaint);
vv.getRenderContext().setEdgeStrokeTransformer(edgeStrokeTransformer);
vv.getRenderContext().setVertexLabelTransformer(new ToStringLabeller());
//vv.getRenderContext().setEdgeLabelTransformer(new ToStringLabeller());
vv.getRenderer().getVertexLabelRenderer().setPosition(Renderer.VertexLabel.Position.CNTR);
JFrame frame = new JFrame("Undirected Graph ");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(vv);
frame.pack();
frame.setVisible(true);
}
Make sure your imports are correct. I used these:
import edu.uci.ics.jung.algorithms.generators.random.BarabasiAlbertGenerator;
import edu.uci.ics.jung.algorithms.layout.CircleLayout;
import edu.uci.ics.jung.algorithms.layout.Layout;
import edu.uci.ics.jung.graph.Graph;
import edu.uci.ics.jung.graph.SparseGraph;
import edu.uci.ics.jung.visualization.BasicVisualizationServer;
import edu.uci.ics.jung.visualization.decorators.ToStringLabeller;
import edu.uci.ics.jung.visualization.renderers.Renderer;
import org.apache.commons.collections15.Factory;
import org.apache.commons.collections15.Transformer;
import org.apache.commons.collections15.functors.ConstantFactory;
import javax.swing.*;
import java.awt.*;
import java.util.HashSet;
In Java you are allowed to do this:
class A {
private final int x;
public A() {
x = 5;
}
}
In Dart, I tried:
class A {
final int x;
A() {
this.x = 5;
}
}
I get two compilation errors:
The final variable 'x' must be initialized.
and
'x' can't be used as a setter because its final.
Is there a way to set final properties in the constructor in Dart?
You cannot instantiate final fields in the constructor body. There is a special syntax for that:
class Point {
final num x;
final num y;
final num distanceFromOrigin;
// Old syntax
// Point(x, y) :
// x = x,
// y = y,
// distanceFromOrigin = sqrt(pow(x, 2) + pow(y, 2));
// New syntax
Point(this.x, this.y) :
distanceFromOrigin = sqrt(pow(x, 2) + pow(y, 2));
}
You can make it even shorter with this. syntax in the constructor (described in https://www.dartlang.org/guides/language/language-tour#constructors):
class Point {
final num x;
final num y;
final num distanceFromOrigin;
Point(this.x, this.y)
: distanceFromOrigin = sqrt(pow(x, 2) + pow(y, 2));
}
If you have some more complicated initialization you should use factory constructor, and the code become:
class Point {
final num x;
final num y;
final num distanceFromOrigin;
Point._(this.x, this.y, this.distanceFromOrigin);
factory Point(num x, num y) {
num distance = distanceFromOrigin = sqrt(pow(x, 2) + pow(y, 2));
return new Point._(x, y, distance);
}
}
Here is a simplified summary of the ways to initialize a final class variable.
class MyClass {
final int x; // <-- initialize this
}
Initializer value
class MyClass {
final int x = 'hello'.length;
}
You'd only use final if the initialization could only be done at runtime. Otherwise, static const is better:
class MyClass {
static const int x = 0;
}
Initializer formal
class MyClass {
MyClass(this.x);
final int x;
}
This is the most common approach.
Initializer list
class MyClass {
MyClass(int x)
: _x = x;
final int _x;
}
This is useful when you want to keep a field private.
Default parameter value
You can surround the parameter with square brackets ([]) for an unnamed parameter or curly braces ({}) for a named parameter and then give it a default value.
class MyClass {
MyClass({this.x = 0});
final int x;
}
This is useful if you want to make the parameter optional.
You could accomplish the same thing with an initializer list as well:
class MyClass {
MyClass({int? x})
: _x = x ?? 0;
final int _x;
}
Late initialization
class MyClass {
MyClass(String? a) {
x = a?.length ?? 0;
}
late final int x;
}
This is useful if you need to do more complex initialization than is allowed in the initializer list. For example, I've done this when initializing a gesture recognizer in Flutter.
Lazy initialization
Another advantage of using late is that it doesn't initialize a value until you access the value.
class MyClass {
late final int x = _doHeavyTask();
int _doHeavyTask() {
var sum = 0;
for (var i = 0; i < 100000000; i++) {
sum += 1;
}
return sum;
}
}
This is useful if you have a heavy calculation that you only want call if you absolutely need it.
This doesn't initialize x:
final myClass = MyClass();
But this does initialize x:
final myClass = MyClass();
final value = myClass.x;
I've had a similar problem: I was trying to initialise a final field from the constructor, while simultaneously calling a super constructor. You could think of the following example
class Point2d {
final int x;
final int y;
Point2d.fromCoordinates(Coordinates coordinates)
: this.x = coordinates.x,
this.y = coordinates.y;
}
class Point3d extends Point2d {
final int z;
Point3d.fromCoordinates(Coordinates coordinates)
:this.z = coordinates.z,
super.fromCoordinates(coordinates);
}
/// Demo class, to simulate constructing an object
/// from another object.
class Coordinates {
final int x;
final int y;
final int z;
}
Well apparently this works. You can initialise your final fields by using the above syntax (check Point3d's constructor) and it works just fine!
Run a small program like this to check:
void main() {
var coordinates = Coordinates(1, 2, 3);
var point3d = Point3d.fromCoordinates(coordinates);
print("x: ${point3d.x}, y: ${point3d.y}, z: ${point3d.z}");
}
It should prin x: 1, y: 2, z: 3
I've come to a dilemma here where I wanted to initialize a final List with no items, and a Stream to be defined inside the constructor (like in this case distanceFromOrigin).
I couldn't do that with any of the answers below, but I mixed them both and it worked.
Example:
class MyBloc {
final BehaviorSubject<List<String>> itemsStream;
final List<String> items = [];
MyBloc() : this.itemsStream = BehaviorSubject<List<String>>.seeded([]) {
items.addAll(List.generate(20, (index) => "Hola! I'm number $index"));
itemsStream.add(items);
}
}
class A{
final int x;
A(this.x){
}
}
Hi I am currently doing my final year project; I need to develop an algorithm visualization tool. I need to cater for user-defined algo; that is animate the algorithm the user types in a text-editor provided in my tool.
I am using the Java Compiler API to compile the code that the user has typed and saved. My tool offers a set of classes that the user can use in his/her algo.
For example:
myArray(this class is provided by my tool)
import java.awt.*;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.accessibility.AccessibleContext;
import javax.swing.*;
public class myArray extends JComponent {
int size = 0;
int count = 0;
int[]hold;
Thread th;
public myArray(int[]arr)//pass user array as parameter
{
//th = new Thread();
size=arr.length;
hold = arr;//make a copy of the array so as to use later in swap operation
}
public int length()
{
return hold.length;
}
public void setAccessibleContext(AccessibleContext accessibleContext) {
this.accessibleContext = accessibleContext;
}
public void paintComponent(Graphics g)
{
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
this.setPreferredSize(new Dimension(360,100));
for(int i=1; i<=size; i++)
{
g2d.drawRect((i*30), 30, 30, 50);
}
for(int i=1; i<=size; i++)
{
g2d.drawString(Integer.toString(hold[i-1]), (i*30)+15, 30+25);
}
}
public void set(int i, int j)//position of the two elements to swap in the array
{
try {
th.sleep(2000);//sleep before swapping because else user won't see original array since it would swap and then sleep
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
int temp = hold[i];
hold[i] = hold[j];
hold[j] = temp;
hold[i]=j;
this.repaint();//can use eapint with a class that extends JPanel
}
public void swap(int i, int j)//position of the two elements to swap in the array
{
try {
th.sleep(2000);//sleep before swapping because else user won't see original array since it would swap and then sleep
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
int temp = hold[i];
hold[i] = hold[j];
hold[j] = temp;
this.repaint();//can use eapint with a class that extends JPanel
}
public int get(int pos)
{
return hold[pos];
}
}
This is a portion of my GUI that will cause the compilation:
JavaCompiler jc = null;
StandardJavaFileManager sjfm = null;
File javaFile = null;
String[] options = null;
File outputDir = null;
URL[] urls = null;
URLClassLoader ucl = null;
Class clazz = null;
Method method = null;
Object object = null;
try
{
jc = ToolProvider.getSystemJavaCompiler();
sjfm = jc.getStandardFileManager(null, null, null);
File[] files = new File[1];
//files[0] = new File("C:/Users/user/Documents/NetBeansProjects/My_Final_Year_Project/myArray.java");
//files[1] = new File("C:/Users/user/Documents/NetBeansProjects/My_Final_Year_Project/Tool.java");
files[0] = new File("C:/Users/user/Documents/NetBeansProjects/My_Final_Year_Project/userDefined.java");
// getJavaFileObjects’ param is a vararg
Iterable fileObjects = sjfm.getJavaFileObjects(files);
jc.getTask(null, sjfm, null, null, null, fileObjects).call();
// Add more compilation tasks
sjfm.close();
options = new String[]{"-d", "C:/Users/user/Documents/NetBeansProjects/My_Final_Year_Project"};
jc.getTask(null, sjfm, null, Arrays.asList(options), null, fileObjects).call();
outputDir = new File("C:/Users/user/Documents/NetBeansProjects/My_Final_Year_Project");
urls = new URL[]{outputDir.toURL()};
ucl = new URLClassLoader(urls);
clazz = ucl.loadClass("userDefined");
method = clazz.getMethod("user", null);
object = clazz.newInstance();
Object ob = method.invoke(object, null);
}
This is an example of a user-defined algo(userDefined.java):
import java.awt.*;
import javax.swing.*;
public class userDefined
{
public void user()
{
int [] numArr = {1,3,1,-1,5,-5,0,7,12,-36};
myArray myArray = new myArray(numArr);
JFrame frame = new JFrame("Rectangles");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.setSize(360, 300);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
frame.add(myArray);
for (int i=myArray.length(); i>1; i--)
{
for (int j=0; j<i-1; j++)
{
if (myArray.get(j) > myArray.get(j+1))
{
myArray.swap(j, j+1);
}
}
}
}
}
The problem I am getting is that if I try to use reflection like above; I only get a white window which does not show the animation) but just displays the result at the very end.
However if I use this instead of reflection(and change the method void user() to static void main(string args) in userDefined.java):
JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
if(compiler.run(null, null, null, "userDefined.java") != 0) {
System.err.println("Could not compile.");
System.exit(0);
}
try {
Runtime rt = Runtime.getRuntime();
Process pr = rt.exec("java "+"userDefined");
BufferedReader input = new BufferedReader(new InputStreamReader(pr.getInputStream()));
String line=null;
while((line=input.readLine()) != null) {
System.out.println(line);
}
} catch(Exception e) {
System.out.println(e.toString());
e.printStackTrace();
it woks provided that after first compilation I place the myArray class in the same folder as the userDefined.java. In this case I can see the animation take place correctly.
How do I use reflection to invoke the main method instead of using an instance of the class.
Please I really need some help with this. Thanks!
You a violating / missusing the first rule of swing: acces swing components only in the EDT (Event Dispatch Thread).
When you start your program using the main method, you are violating that rule. This happens to work, but might have all kinds of weird effects. This is not a theoretic warning, it happend to me and it is not nice.
When you run it using reflection from your code, you are most likely in the EDT, so your algorithm runs completely before the GUI gets updated again (which also happens on the EDT). Thats why you see only the final result of the algorithm.
The correct way to do this would be:
Run the algorithm in a seperate thread and make sure all changes to your myArray Component happen in the EDT, using SwingUtilities.invokeAndWait or SwingUtilities.invokeLater
I am trying to build an android application for a message board. To display formatted html for the post contents I have chosen the TextView and the Html.fromHtml() method. That, unfortunately, covers only a few html tags. The unknown tags are handled by a class that implements TagHandler and has to be generated by myself.
Now, I googled a lot and can't find an example of how this class should work. Let's consider I have an u tag for underlining some text (I know that this is deprecated, but whatever). How does my TagHandler look like?
It is called in the following way:
public void handleTag(boolean opening, String tag, Editable output, XMLReader xmlReader) {
The first two arguments are fine. I guess I have to modify output using output.append(). But how do I attach something underlined there?
So, i finally figured it out by myself.
public class MyHtmlTagHandler implements TagHandler {
public void handleTag(boolean opening, String tag, Editable output, XMLReader xmlReader) {
if(tag.equalsIgnoreCase("strike") || tag.equals("s")) {
processStrike(opening, output);
}
}
private void processStrike(boolean opening, Editable output) {
int len = output.length();
if(opening) {
output.setSpan(new StrikethroughSpan(), len, len, Spannable.SPAN_MARK_MARK);
} else {
Object obj = getLast(output, StrikethroughSpan.class);
int where = output.getSpanStart(obj);
output.removeSpan(obj);
if (where != len) {
output.setSpan(new StrikethroughSpan(), where, len, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
}
}
}
private Object getLast(Editable text, Class kind) {
Object[] objs = text.getSpans(0, text.length(), kind);
if (objs.length == 0) {
return null;
} else {
for(int i = objs.length;i>0;i--) {
if(text.getSpanFlags(objs[i-1]) == Spannable.SPAN_MARK_MARK) {
return objs[i-1];
}
}
return null;
}
}
}
And for your TextView you can call this like:
myTextView.setText (Html.fromHtml(text.toString(), null, new MyHtmlTagHandler()));
if anybody needs it.
Cheers
This solution is found in the Android sdk
In android.text.html. Lines 596 - 626. Copy/pasted
private static <T> Object getLast(Spanned text, Class<T> kind) {
/*
* This knows that the last returned object from getSpans()
* will be the most recently added.
*/
Object[] objs = text.getSpans(0, text.length(), kind);
if (objs.length == 0) {
return null;
} else {
return objs[objs.length - 1];
}
}
private static void start(SpannableStringBuilder text, Object mark) {
int len = text.length();
text.setSpan(mark, len, len, Spannable.SPAN_MARK_MARK);
}
private static <T> void end(SpannableStringBuilder text, Class<T> kind,
Object repl) {
int len = text.length();
Object obj = getLast(text, kind);
int where = text.getSpanStart(obj);
text.removeSpan(obj);
if (where != len) {
text.setSpan(repl, where, len, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
}
}
To use, override TagHandler like so:
public void handleTag(boolean opening, String tag, Editable output, XMLReader xmlReader) {
if(tag.equalsIgnoreCase("strike") || tag.equals("s")) {
if(opening){
start((SpannableStringBuilder) output, new Strike();
} else {
end((SpannableStringBuilder) output, Strike.class, new StrikethroughSpan());
}
}
}
/*
* Notice this class. It doesn't really do anything when it spans over the text.
* The reason is we just need to distinguish what needs to be spanned, then on our closing
* tag, we will apply the spannable. For each of your different spannables you implement, just
* create a class here.
*/
private static class Strike{}
I took janoliver's answer and came up with my version that attempts to support more options
String text = ""; // HTML text to convert
// Preprocessing phase to set up for HTML.fromHtml(...)
text = text.replaceAll("<span style=\"(?:color: (#[a-fA-F\\d]{6})?; )?(?:font-family: (.*?); )?(?:font-size: (.*?);)? ?\">(.*?)</span>",
"<font color=\"$1\" face=\"$2\" size=\"$3\">$4</font>");
text = text.replaceAll("(?<=<font color=\"#[a-fA-F0-9]{6}\" )face=\"'(.*?)', .*?\"", "face=\"$1\"");
text = text.replaceAll("(?<=<font color=\"#[a-fA-F0-9]{6}\" )(face=\".*?\" )size=\"xx-small\"", "$1size=\"1\"");
text = text.replaceAll("(?<=<font color=\"#[a-fA-F0-9]{6}\" )(face=\".*?\" )size=\"x-small\"", "$1size=\"2\"");
text = text.replaceAll("(?<=<font color=\"#[a-fA-F0-9]{6}\" )(face=\".*?\" )size=\"small\"", "$1size=\"3\"");
text = text.replaceAll("(?<=<font color=\"#[a-fA-F0-9]{6}\" )(face=\".*?\" )size=\"medium\"", "$1size=\"4\"");
text = text.replaceAll("(?<=<font color=\"#[a-fA-F0-9]{6}\" )(face=\".*?\" )size=\"large\"", "$1size=\"5\"");
text = text.replaceAll("(?<=<font color=\"#[a-fA-F0-9]{6}\" )(face=\".*?\" )size=\"x-large\"", "$1size=\"6\"");
text = text.replaceAll("(?<=<font color=\"#[a-fA-F0-9]{6}\" )(face=\".*?\" )size=\"xx-large\"", "$1size=\"7\"");
text = text.replaceAll("<strong>(.*?)</strong>", "<_em>$1</_em>"); // we use strong for bold-face
text = text.replaceAll("<em>(.*?)</em>", "<strong>$1</strong>"); // and em for italics
text = text.replaceAll("<_em>(.*?)</_em>", "<em>$1</em>"); // but Android uses em for bold-face
text = text.replaceAll("<span style=\"background-color: #([a-fA-F0-9]{6}).*?>(.*?)</span>", "<_$1>$2</_$1>");
text_view.setText(Html.fromHtml(text, null, new Html.TagHandler() {
private List<Object> _format_stack = new LinkedList<Object>();
#Override
public void handleTag(boolean open_tag, String tag, Editable output, XMLReader _) {
if (tag.startsWith("ul"))
processBullet(open_tag, output);
else if (tag.matches(".[a-fA-F0-9]{6}"))
processBackgroundColor(open_tag, output, tag.substring(1));
}
private void processBullet(boolean open_tag, Editable output) {
final int length = output.length();
if (open_tag) {
final Object format = new BulletSpan(BulletSpan.STANDARD_GAP_WIDTH);
_format_stack.add(format);
output.setSpan(format, length, length, Spanned.SPAN_MARK_MARK);
} else {
applySpan(output, length, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
}
}
private void processBackgroundColor(boolean open_tag, Editable output, String color) {
final int length = output.length();
if (open_tag) {
final Object format = new BackgroundColorSpan(Color.parseColor('#' + color));
_format_stack.add(format);
output.setSpan(format, length, length, Spanned.SPAN_MARK_MARK);
} else {
applySpan(output, length, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
}
}
private Object getLast(Editable text, Class kind) {
#SuppressWarnings("unchecked")
final Object[] spans = text.getSpans(0, text.length(), kind);
if (spans.length != 0)
for (int i = spans.length; i > 0; i--)
if (text.getSpanFlags(spans[i-1]) == Spannable.SPAN_MARK_MARK)
return spans[i-1];
return null;
}
private void applySpan(Editable output, int length, int flags) {
if (_format_stack.isEmpty()) return;
final Object format = _format_stack.remove(0);
final Object span = getLast(output, format.getClass());
final int where = output.getSpanStart(span);
output.removeSpan(span);
if (where != length)
output.setSpan(format, where, length, flags);
}
}));
This does seem to get the bullets, foreground color, and background color. It might work for the font-face but you might need to supply the fonts as it doesn't seem that Android supports fonts other than Droid/Roboto.
This is more of a proof-of-concept, you might probably want to convert the regex into String processing, since regex doesn't support combining the preprocessing in any way, meaning this takes a lot of passes over the String. This also doesn't seem to get the font size to change, I've tried defining it like "16sp", "medium", or "4" without seeing changes. If anyone has gotten sizes to work, mind sharing?
I currently would like to be able to add numbered/ordered list support to this, i.e.
item
item
item
NOTE:
To people starting with any of this, it seems that the "tag" that is given to handleTag(...) is just the name of the tag (like "span"), and doesn't contain any of the attributes assigned in the tag (like if you have "), you can see my loophole around this for the background color.
We have been developing internally this library https://github.com/square1-io/rich-text-android for a while now and we use it in a number of content intensive news apps.
The library can parse most common html tags including video and img with remote download of images.
A custom view, RichTextView can then be used as a replacement of TextView to display the parsed content.
We have released it publicly just recently so the doc is still incomplete however the example provided should be easy to follow to see if it fit your needs.
Although I can see it it in Html.java API that style and text-align should be usable with the tags <p> , <div> etc. I am failing to get it to work with <p align="center"> or <p style="text-align: center"> and many other variants. Not being able to do this center alignment of text, and other styles like font size, multiple font faces from my ttf files, background colour, I have made my own htmlTextView based on TextView but with my own tagHandler class. Given one or two minor irritations, most of the tags are fine but my custom alignment tags, left, centre, right work only in special conditions (that I don't understand), otherwise. they don't work or crash the app! This is my alignment tag handle. It has the same structure as all the other custom tag handlers but really behaves weirdly! The basic form of my tag handlers are the same and are not conceived by me! I found the taghandler template after many hours searching on the web. I am grateful to whoever it was that posted it but my memory and organisational ability are such that I can't really remember who or where, so if you recognise this code as yours please let me know. The only link (which is here) I have is in my code: stackoverflow: Android: How to use the Html.TagHandler?
private void ProcessAlignment(Layout.Alignment align, boolean opening, Editable output) {
int len = output.length();
if (opening) {
output.setSpan(new AlignmentSpan.Standard(align), len, len, Spannable.SPAN_MARK_MARK);
} else {
Object obj = getLast(output, AlignmentSpan.Standard.class);
int where = output.getSpanStart(obj);
output.removeSpan(obj);
if (where != len) {
output.setSpan(new AlignmentSpan.Standard(align), where, len, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
}
}
}
I think the problem is that the end tag is not getting connected the correct start tag.
private Object getLast(Editable text, Class kind) {
Object[] objs = text.getSpans(0, text.length(), kind);
if (objs.length == 0) {
return null;
} else {
for (int i = objs.length - 1; i >= 0; --i) {
if (text.getSpanFlags(objs[i]) == Spannable.SPAN_MARK_MARK) {
return objs[i];
}
}
return null;
}
}
This is the total class and something is not right. The largest component is my understanding! Perhaps someone can help me understand better...
public class htmlTextView extends AppCompatTextView {
static Typeface mLogo;
static Typeface mGAMZ;
static Typeface mChalk;
static Typeface mSouvenir;
int GS_PAINTFLAGS = FILTER_BITMAP_FLAG | ANTI_ALIAS_FLAG | SUBPIXEL_TEXT_FLAG | HINTING_ON;
public htmlTextView(Context context) {
super(context);
initialise();
}
public htmlTextView(Context context, #Nullable AttributeSet attrs) {
super(context, attrs);
initialise();
}
public htmlTextView(Context context, #Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
initialise();
}
private void initialise() {
mLogo = Typeface.createFromAsset(theAssetManager, "fonts/logo.ttf");
mGAMZ = Typeface.createFromAsset(theAssetManager, "fonts/GAMZ One.ttf");
mChalk = Typeface.createFromAsset(theAssetManager, "fonts/swapfix.ttf");
mSouvenir = Typeface.createFromAsset(theAssetManager, "fonts/Souvenir Regular.ttf");
setPaintFlags(GS_PAINTFLAGS);
}
public void setDefaultTypefaceSouvenir() {
setTypeface(mSouvenir);
}
public void setDefaultTypefaceGAMZ() {
setTypeface(mGAMZ);
}
public void setDefaultTypefaceChalk() {
setTypeface(mChalk);
}
/*public myTextView(Context context, #Nullable AttributeSet attrs, int defStyleAttr, int defStyleRes) {
super(context, attrs, defStyleAttr, defStyleRes);
}*/
public void setHTML(String htmltext) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) { // Nougat API 24
setText(Html.fromHtml(htmltext, Html.FROM_HTML_MODE_LEGACY,
null, new TypefaceTagHandler()));
} else {
setText(Html.fromHtml(htmltext, null, new TypefaceTagHandler()));
}
}
#Override
protected void dispatchDraw(Canvas canvas) {
super.dispatchDraw(canvas);
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
}
#Override
public Bitmap getDrawingCache(boolean autoScale) {
return super.getDrawingCache(autoScale);
}
#Override
public void draw(Canvas canvas) {
super.draw(canvas);
}
// http://stackoverflow.com/questions/4044509/android-how-to-use-the-html-taghandler
private static class TypefaceTagHandler implements Html.TagHandler {
private void ProcessAlignment(Layout.Alignment align, boolean opening, Editable output) {
int len = output.length();
if (opening) {
output.setSpan(new AlignmentSpan.Standard(align), len, len, Spannable.SPAN_MARK_MARK);
} else {
Object obj = getLast(output, AlignmentSpan.Standard.class);
int where = output.getSpanStart(obj);
output.removeSpan(obj);
if (where != len) {
output.setSpan(new AlignmentSpan.Standard(align), where, len, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
}
}
}
private void ProcessTypefaceTag(Typeface tf, boolean opening, Editable output) {
int len = output.length();
if (opening) {
output.setSpan(new CustomTypefaceSpan("", tf), len, len,
Spannable.SPAN_MARK_MARK);
} else {
Object obj = getLast(output, CustomTypefaceSpan.class);
int where = output.getSpanStart(obj);
output.removeSpan(obj);
if (where != len) {
output.setSpan(new CustomTypefaceSpan("", tf), where, len,
Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
}
}
}
private void ProcessScaleTag(float scalefactor, boolean opening, Editable output) {
int len = output.length();
if (opening) {
output.setSpan(new RelativeSizeSpan(scalefactor), len, len,
Spannable.SPAN_MARK_MARK);
} else {
Object obj = getLast(output, RelativeSizeSpan.class);
int where = output.getSpanStart(obj);
output.removeSpan(obj);
if (where != len) {
output.setSpan(new RelativeSizeSpan(scalefactor), where, len,
Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
}
}
}
private void ProcessBox(int colour, boolean opening, Editable output) {
int len = output.length();
if (opening) {
output.setSpan(new BackgroundColorSpan(colour), len, len,
Spannable.SPAN_MARK_MARK);
} else {
Object obj = getLast(output, BackgroundColorSpan.class);
int where = output.getSpanStart(obj);
output.removeSpan(obj);
if (where != len) {
output.setSpan(new BackgroundColorSpan(colour), where, len,
Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
}
}
}
private void ProcessTextColour(int colour, boolean opening, Editable output) {
int len = output.length();
if (opening) {
output.setSpan(new ForegroundColorSpan(colour), len, len,
Spannable.SPAN_MARK_MARK);
} else {
Object obj = getLast(output, ForegroundColorSpan.class);
int where = output.getSpanStart(obj);
output.removeSpan(obj);
if (where != len) {
output.setSpan(new ForegroundColorSpan(colour), where, len,
Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
}
}
}
final HashMap<String, String> attributes = new HashMap<>();
#Override
public void handleTag(boolean opening, String tag, Editable output, XMLReader xmlReader) {
String Attr = "";
//if (!opening) attributes.clear();
processAttributes(xmlReader);
if ("txt".equalsIgnoreCase(tag)) {
Attr = attributes.get("clr");
System.out.println("clr Attr: " + Attr + ", opening: " + opening);
if (Attr == null || Attr.isEmpty()
|| "black".equalsIgnoreCase(Attr)
|| Attr.charAt(0) == 'k') {
System.out.println("did black, opening: " + opening);
ProcessTextColour(parseColor("#000000"), opening, output);
} else {
if (Attr.equalsIgnoreCase("g")) {
ProcessTextColour(parseColor("#b2b3b3"), opening, output);
} else {
System.out.println("did colour, opening: " + opening);
ProcessTextColour(parseColor(Attr), opening, output);
}
}
return;
}
if ("box".equalsIgnoreCase(tag)) {
ProcessBox(parseColor("#d7d6d5"), opening, output);
return;
}
if ("scl".equalsIgnoreCase(tag)) {
Attr = attributes.get("fac");
System.out.println("scl Attr: " + Attr);
if (Attr != null && !Attr.isEmpty()) {
ProcessScaleTag(parseFloat(Attr), opening, output);
}
return;
}
if ("left".equalsIgnoreCase(tag)) {
ProcessAlignment(Layout.Alignment.ALIGN_NORMAL, opening, output);
return;
}
if ("centre".equalsIgnoreCase(tag)) {
ProcessAlignment(Layout.Alignment.ALIGN_CENTER, opening, output);
return;
}
if ("right".equalsIgnoreCase(tag)) {
ProcessAlignment(Layout.Alignment.ALIGN_OPPOSITE, opening, output);
return;
}
if ("logo".equalsIgnoreCase(tag)) {
ProcessTypefaceTag(mLogo, opening, output);
return;
}
if ("gamz".equalsIgnoreCase(tag)) {
ProcessTypefaceTag(mGAMZ, opening, output);
return;
}
if ("chalk".equalsIgnoreCase(tag)) {
System.out.println("chalk " + (opening ? "opening" : "closing"));
ProcessTypefaceTag(mChalk, opening, output);
return;
}
}
private Object getLast(Editable text, Class kind) {
Object[] objs = text.getSpans(0, text.length(), kind);
if (objs.length == 0) {
return null;
} else {
for (int i = objs.length - 1; i >= 0; --i) {
if (text.getSpanFlags(objs[i]) == Spannable.SPAN_MARK_MARK) {
return objs[i];
}
}
return null;
}
}
private void processAttributes(final XMLReader xmlReader) {
try {
Field elementField = xmlReader.getClass().getDeclaredField("theNewElement");
elementField.setAccessible(true);
Object element = elementField.get(xmlReader);
Field attsField = element.getClass().getDeclaredField("theAtts");
attsField.setAccessible(true);
Object atts = attsField.get(element);
Field dataField = atts.getClass().getDeclaredField("data");
dataField.setAccessible(true);
String[] data = (String[])dataField.get(atts);
Field lengthField = atts.getClass().getDeclaredField("length");
lengthField.setAccessible(true);
int len = (Integer)lengthField.get(atts);
/**
* MSH: Look for supported attributes and add to hash map.
* This is as tight as things can get :)
* The data index is "just" where the keys and values are stored.
*/
for(int i = 0; i < len; i++)
attributes.put(data[i * 5 + 1], data[i * 5 + 4]);
}
catch (Exception e) {
Log.d(TAG, "Exception: " + e);
}
}
}
private static class CustomTypefaceSpan extends TypefaceSpan {
private final Typeface newType;
public CustomTypefaceSpan(String family, Typeface type) {
super(family);
newType = type;
}
#Override
public void updateDrawState(TextPaint ds) {
applyCustomTypeFace(ds, newType);
}
#Override
public void updateMeasureState(TextPaint paint) {
applyCustomTypeFace(paint, newType);
}
private void applyCustomTypeFace(Paint paint, Typeface tf) {
int oldStyle;
Typeface old = paint.getTypeface();
if (old == null) {
oldStyle = 0;
} else {
oldStyle = old.getStyle();
}
int fake = oldStyle & ~tf.getStyle();
if ((fake & Typeface.BOLD) != 0) {
paint.setFakeBoldText(true);
}
if ((fake & Typeface.ITALIC) != 0) {
paint.setTextSkewX(-0.25f);
}
paint.setTypeface(tf);
}
}
}
The htmlTextView is created from the activity with:
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
theAssetManager = getAssets();
htmlTextView tv = new htmlTextView(this);
tv.setDefaultTypefaceSouvenir();
tv.setTextColor(BLACK);
tv.setBackgroundColor(0xfff0f0f0);
tv.setPadding(4, 4, 4, 4);
tv.setTextSize(30);
tv.setMovementMethod(new ScrollingMovementMethod());
tv.setHTML(getString(R.string.htmljumblies));
//tv.setHTML(getString(R.string.htmltest));
RelativeLayout rl = (RelativeLayout) findViewById(R.id.rl);
rl.addView(tv);
}
and htmljumblies is defined in strings.xml as below. This particular version will crash the app but if the first <centre>, </centre> tags are removed from lines 7 and 9, The Jumblies will appear centralised? Confusing and frustrating! Keep them and remove the <centre>, </centre> tags enfolding The Jumblies and nothing happens. The line in the header is not centrally aligned!
<string name="htmljumblies">
<![CDATA[⟹<logo><scl fac="1.1"><font color="#e5053a">GAMZ</font></scl></logo>
<chalk><scl fac="1.8"> SWAP </scl></chalk>
<scl fac="1.00">Set <b>1</b>, Game <b>1</b></scl>
<br>
<centre>
<gamz><font color="#e5053a"><scl fac="1.50">a</scl></font><scl fac="0.90">(9)</scl></gamz>, <gamz><font color="#00a3dd"><scl fac="1.50">e</scl></font><scl fac="0.90">(8)</scl></gamz>, <gamz><font color="#fba311"><scl fac="1.50">i</scl></font><scl fac="0.90">(8)</scl></gamz>, <gamz><font color="#bc5e1e"><scl fac="1.50">o</scl></font><scl fac="0.90">(8)</scl></gamz>, <gamz><font color="#bf30b5"><scl fac="1.50">u</scl></font><scl fac="0.90">(9)</scl></gamz>
</centre>
<br>
This is an example of my custom <b>htmlTextView</b> drawn from HTML format
text with custom tags to use custom fonts, colouring typeface sizing and highlight boxes.
The default font is <b><i>Souvenir</i></b>, but 3 other fonts are used:<br>
The <font color="#e5053a"><b><logo><scl fac="1.1">GAMZ</scl></logo></b></font>
<font color="#000080"><gamz><scl fac="0.8"><box>letter</box>
<box>fonts</box><sc></gamz></font>
and <chalk><scl fac="1.8">swapfix</scl></chalk>, essentially
<chalk><scl fac="0.9">Staccato 555</scl></chalk>,
as used in the words <chalk><scl fac="1.2">SWAP</scl></chalk> and
<chalk><scl fac="1.2">FIX</scl></chalk>
on the <font color="#e5053a"><b><logo><scl fac="1.1">GAMZ</scl></logo></b></font>
boxes.
<br>
<centre>
<scl fac="2"><box><b> <u>The Jumblies</u> </b></box></scl><br>
<font color="#0000ff">
They went to sea in a Sieve, they did,<br>
In a Sieve they went to sea:<br>
In spite of all their friends could say,<br>
On a winter\'s morn, on a stormy day,<br>
In a Sieve they went to sea!<br>
And when the Sieve turned round and round,<br>
And every one cried, \'You\'ll all be drowned!\'<br>
They called aloud, \'Our Sieve ain\'t big,<br>
But we don\'t care a button! we don\'t care a fig!<br>
In a Sieve we\'ll go to sea!\'<br>
Far and few, far and few,<br>
Are the lands where the Jumblies live;<br>
Their heads are green, and their hands are blue,<br>
And they went to sea in a Sieve.<br>
<br>
They sailed away in a Sieve, they did,<br>
In a Sieve they sailed so fast,<br>
With only a beautiful pea-green veil<br>
Tied with a riband by way of a sail,<br>
To a small tobacco-pipe mast;<br>
And every one said, who saw them go,<br>
\'O won\'t they be soon upset, you know!<br>
For the sky is dark, and the voyage is long,<br>
And happen what may, it\'s extremely wrong<br>
In a Sieve to sail so fast!\'<br>
Far and few, far and few,<br>
Are the lands where the Jumblies live;<br>
Their heads are green, and their hands are blue,<br>
And they went to sea in a Sieve.<br>
<br>
The water it soon came in, it did,<br>
The water it soon came in;<br>
So to keep them dry, they wrapped their feet<br>
In a pinky paper all folded neat,<br>
And they fastened it down with a pin.<br>
And they passed the night in a crockery-jar,<br>
And each of them said, \'How wise we are!<br>
Though the sky be dark, and the voyage be long,<br>
Yet we never can think we were rash or wrong,<br>
While round in our Sieve we spin!\'<br>
Far and few, far and few,<br>
Are the lands where the Jumblies live;<br>
Their heads are green, and their hands are blue,<br>
And they went to sea in a Sieve.<br>
<br>
And all night long they sailed away;<br>
And when the sun went down,<br>
They whistled and warbled a moony song<br>
To the echoing sound of a coppery gong,<br>
In the shade of the mountains brown.<br>
\'O Timballo! How happy we are,<br>
When we live in a Sieve and a crockery-jar,<br>
And all night long in the moonlight pale,<br>
We sail away with a pea-green sail,<br>
In the shade of the mountains brown!\'<br>
Far and few, far and few,<br>
Are the lands where the Jumblies live;<br>
Their heads are green, and their hands are blue,<br>
And they went to sea in a Sieve.<br>
<br>
They sailed to the Western Sea, they did,<br>
To a land all covered with trees,<br>
And they bought an Owl, and a useful Cart,<br>
And a pound of Rice, and a Cranberry Tart,<br>
And a hive of silvery Bees.<br>
And they bought a Pig, and some green Jack-daws,<br>
And a lovely Monkey with lollipop paws,<br>
And forty bottles of Ring-Bo-Ree,<br>
And no end of Stilton Cheese.<br>
Far and few, far and few,<br>
Are the lands where the Jumblies live;<br>
Their heads are green, and their hands are blue,<br>
And they went to sea in a Sieve.<br>
<br>
And in twenty years they all came back,<br>
In twenty years or more,<br>
And every one said, \'How tall they\'ve grown!<br>
For they\'ve been to the Lakes, and the Torrible Zone,<br>
And the hills of the Chankly Bore!\'<br>
And they drank their health, and gave them a feast<br>
Of dumplings made of beautiful yeast;<br>
And every one said, \'If we only live,<br>
We too will go to sea in a Sieve,---<br>
To the hills of the Chankly Bore!\'<br>
Far and few, far and few,<br>
Are the lands where the Jumblies live;<br>
Their heads are green, and their hands are blue,<br>
And they went to sea in a Sieve.</centre></font>
]]>
</string>