I am using processing to draw lines on canvas. My code is quite simple:
processing.line(line.origin.x, line.origin.y, line.destination.x, line.destination.y);`
But I get pixelated lines:
How do I draw non-pixelated precise lines?
If your line code is inside your draw function it will be pixelated unless you add a background color above it.
So you can add a background color in your draw function or you could instead put your line code in the setup function. Either should remove the pixelation.
Related
I want to mask the png image pattern.png with another image - mask.png, but it doesn't work at all and I can't find the reason. Instead of masking the image, the mask just disappears and the pattern stays the same as it was.
I tried making a MovieClip, drawing e.g. a circle and using that as the mask instead of mask.png and it works just fine. Is it because you can't use loader objects as masks? How do I make it work?
edit: After changing the size of mask.png to be smaller than the pattern, I've realized that it actually does kind of work, but what happens is instead of cutting the pattern into the shape I've drawn in the png file it just cuts it into the shape of the entire file, as in, it counts the rectangular transparent background as well. How can I make it cut out just the shape?
var mask:Loader = new Loader();
mask.load(new URLRequest("mask.png"));
var pattern:Loader = new Loader();
pattern.load(new URLRequest("pattern.png"));
pattern.contentLoaderInfo.addEventListener(Event.COMPLETE, loadComplete);
function loadComplete(e:Event):void {
addChild(pattern);
addChild(mask);
pattern.mask = mask;
}
Your code is looks correctly. The mask property of DisplayObject wants DisplayObject too. But try to make few things, to find the trouble:
You have only one listener, to pattern.png. But you must be sure, that mask.png has loaded already too.
Despite that Loader is DisplayObject too - try to get content from loader for mask, and just after that try to use it.
*Ah, and one more thing. You must at first add listener, and only later try to load.
Is it possible to only trigger a div's mouseover when the cursor is over an opaque part of the div's background image? Perhaps via Javascript?
All I can find with Google are old IE PNG fixes.
This looks like a similar question to this one: Hit detection on non-transparent pixel
I suppose this could also be done for background image by getting the attribute with jQuery:
$('#myDiv').css('background-image');
I haven't personally done this, but it seems like a viable solution. This will only work for modern browsers, but you should be able to make it back-compatible with excanvas.
It is possible, just not very easily. You'll have to use a lot of Javascript.
You'd want to attach to your <div>'s onmousemove event, which returns the X,Y coordinates of the cursor. Your event handler function would then test to see if the cursor is in the correct place in order to trigger an alternative onmouseover event.
Implementing the "is the cursor over an opaque pixel or not?" test can be done two ways: the first is to create a simple mathematical expression (say if the opaque parts of the image make neat rectangles, circles or polygons). The more difficult (and less browser-supported) way is to load the background image into a Canvas object and then get the current pixel value's opacity figure and take it from there, like so:
var pixel = canvas.getImageData(x, y, 1, 1).data;
var alpha = pixel[3]; // assuming RGBA
if( alpha > threshold ) onMouseOver(); // raise the event
Another alternative is to create an entirely transparent div (or some other element) positioned and sized so that it only covers the opaque part of the div below, then just test the mouseover of that element's box.
It's a bit of tweaking but why don't you add a class to your opaque div, and use JavaScript to check for it?
In jQuery:
$('div').mouseover(function(){
if ($(this).is('.opaque')) {
//Some actions
}
});
I would like to draw a multiple segment line on a html 5 canvas with variable width per segment.
I tried something like (pseudocode):
beginpath()
setLineWidth(1)
lineTo(0,0)
...
setLineWidth(10)
lineTo(73, 44)
stroke()
but it seems stroke only takes the last linewidth() value? Is there another way?
I tried making every segment its own line, but that turned out really really show when drawing 1000+ segments.
You have to call stroke() on each segment, not at the very end and there is no other possiblity.
Probably will have to make each segment it's own line. That or figure out how to make a custom shape with the same sort of gradient.
I have a BitmapData object named myBitmapData. It was loaded of PNG of size 104x104. This PNG represents a red circle on the transparent background.
There is also a Sprite object named myBackground. I want render that red circle into myBackground.
myBackground.graphics.beginBitmapFill(myBitmapData);
myBackground.graphics.drawRect(0, 0, myBitmapData.width, myBitmapData.height);
myBackground.graphics.endFill();
addChild(myBackground);
Everything is fine. I see a red circle in the left top of myBackground.
But when I change the third line to
myBackground.graphics.drawRect(0, 52, myBitmapData.width, myBitmapData.height);
and expect my circle to be translated 52 pixels down, I actually obtain something strange (for me :)): there are two red half-circles (they form like hourglass).
So, the question is: how do I render myBitmapData into the random position of myBackground?
P.S.
In the case of
myBackground.graphics.drawRect(0, 104, myBitmapData.width, myBitmapData.height);
it is circle again :)
This is caused by beginBitmapFill's default repeat = true parameter. There's an example in the docs. Disabling the repetition won't work though, you'd just get a half circle then.
There are several ways to fix this:
Use a Matrix with a translation (displacement) as argument in beginBitmapFill.
Draw the rectangle at 0,0 on another Sprite, and move that sprite to where you want it on the background.
Don't draw directly to the background, but to another bitmap using copyPixels. Then fill the background with that bitmap.
The reason for asking this question is because I want to be able to draw an arrow between two svg images. I want to use canvas to create the arrows, so firstly I generate the svgs then place a canvas on top of them to be able to draw the arrows.
I've tried using style=... but haven't had any luck as everytime I add the canvas element it just pushes my svg images to another pl
If there's no easy way to do this I'll just create arrows using SVG, I figured it would be more efficient to use canvas if I had to do lots of arrows in a short amount of time.
You need position:absolute on the CSS for the canvas to take it out of the flow, and then you can layer it as you like using z-index.
However, I instead suggest that you can use one or two tiny canvases to create the arrowheads and use toDataURL() on them to create a url you can use for <image> tags in the SVG. This way all your graphics are in SVG but you can use the canvas for complex raster effects if you need to.
have you tried z-index? it's a useful css trick
#svgcontent
{
z-index:1
}
#html5content
{
z-index:3
}
EDIT: accidentally screwed the #s up. 'scuse me.