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digitalmars.D.learn - DLangUI: Rendering a generated image

reply "Alex Parrill" <initrd.gz gmail.com> writes:
What is the simplest way of rendering an application-generated 
image using DLangUI?

I'm trying to render the outputs of some noise-generating 
functions, along with some controls to alter the parameters of 
that function. I didn't see an ImageWidget anywhere, so I tried 
making my own that takes in a DrawBuf. The code is below.

When the `buf.drawRescaled` line in the `onDraw` method is 
commented out, the `buf.drawLine` will render a line over where 
the widget would be located. But when the `drawRescaled` line is 
uncommented, the entire window becomes white; not even the line 
drawn afterwards is visible.

What am I doing wrong? Alternatively, is there a simpler way that 
I'm not thinking of or don't see?

	import std.stdio;

	import dlangui;


	enum W = 512;
	enum H = 512;

	final class CanvasWidget : Widget {
		private DrawBuf canvas;
		this(DrawBuf canvas) {
			this.canvas = canvas;
		override void onDraw(DrawBuf buf) {
			if (visibility != Visibility.Visible)
			Rect rc = _pos;
			//buf.drawRescaled(rc, canvas, Rect(0,0,canvas.width, 
			buf.drawLine(Point(rc.left, rc.top), Point(rc.right, 
rc.bottom), 0xff0000);
			_needDraw = false;

	void draw(ColorDrawBuf img) {
		for(int y=0; y<img.height; y++) {
			auto scanline = img.scanLine(y);
			for(uint x=0; x<img.width; x++) {
				scanline[x] = 0xFF0000;

	//void main() {
	extern(C) int UIAppMain(string[] args) {
		Platform.instance.resourceDirs = [];
		Platform.instance.uiLanguage = "en";
		Platform.instance.uiTheme = "theme_default";
		Window window = Platform.instance.createWindow("Window", null);
		VerticalLayout baseLayout = new VerticalLayout();
		baseLayout.layoutWidth = FILL_PARENT;
		baseLayout.layoutHeight = FILL_PARENT;
		window.mainWidget = baseLayout;
		auto img = new ColorDrawBuf(W,H);
		Widget canvas = new CanvasWidget(img);
		canvas.layoutWidth = W;
		canvas.layoutHeight = H;
		baseLayout.addChild((new Button())
		return Platform.instance.enterMessageLoop();
Apr 14 2015
parent "Alex Parrill" <initrd.gz gmail.com> writes:
I found the `ImageWidget` class in controls.d, but I'm still 
having the same issue.

Tweaked code (replaced the section between `window.mainWidget = 
baseLayout;` and `baseLayout.addChild((new Button())...`

	auto img = Ref!DrawBuf(new ColorDrawBuf(W,H));
	draw(cast(ColorDrawBuf) (img.get));
	auto drawableImg = Ref!ImageDrawable(new ImageDrawable(img));
	auto canvas = new ImageWidget();
	canvas.drawable = drawableImg;
Apr 14 2015