Java Code Examples for com.google.gwt.canvas.client.Canvas#createIfSupported()

Canvas createImageCanvas(int [] pixels, int width, int height) {

	    Canvas canvas = Canvas.createIfSupported();
	    canvas.setCoordinateSpaceWidth(width);
	    canvas.setCoordinateSpaceHeight(height);

	    Context2d context = canvas.getContext2d();
	    ImageData data = context.createImageData(width, height);

	    CanvasPixelArray array = data.getData();
	    for(int i=0; i<width*height; i++) {
	        array.set(4*i+0, pixels[i] & 0xFF);
	        array.set(4*i+1, (pixels[i] >> 8) & 0xFF);
	        array.set(4*i+2, (pixels[i] >> 16) & 0xFF);
	        array.set(4*i+3, (pixels[i] >> 24) & 0xFF);
	    }
	    context.putImageData(data, 0, 0);

	    return canvas;

	}
 

private Canvas createImageCanvas(int [] pixels, int width, int height) {
	
	Canvas canvas = Canvas.createIfSupported();
	canvas.setCoordinateSpaceWidth(width);
	canvas.setCoordinateSpaceHeight(height);
	
	Context2d context = canvas.getContext2d();
	ImageData data = context.createImageData(width, height);

	CanvasPixelArray array = data.getData();
	for(int i=0; i<width*height; i++) { // ABGR
		array.set(4*i+0, pixels[i] & 0xFF);
		array.set(4*i+1, (pixels[i] >> 8) & 0xFF);
		array.set(4*i+2, (pixels[i] >> 16) & 0xFF);
		array.set(4*i+3, (pixels[i] >> 24) & 0xFF);
	}
	context.putImageData(data, 0, 0);
	
	canvas.getElement().getStyle().setMargin(4, Unit.PX);
	
	return canvas;
	
}
 

public static CanvasElement createImage(int width, int height) {
	Canvas canvas = Canvas.createIfSupported();
	canvas.setWidth(width + "px");
	canvas.setCoordinateSpaceWidth(width);
	canvas.setHeight(height + "px");
	canvas.setCoordinateSpaceHeight(height);
	return canvas.getCanvasElement();
}
 

private Widget prepareCanvas() {
	canvas = Canvas.createIfSupported();
	if (canvas == null) {
		// TODO
		throw new RuntimeException("Canvas not supported!");
	}
	canvas.setTabIndex(0);

	final SimplePanel panel = new SimplePanel(canvas);
	panel.setStyleName("content");

	Window.addResizeHandler(e -> resizeCanvas());
	Scheduler.get().scheduleFinally(() -> resizeCanvas());
	return panel;
}
 

public Canvas getCircuitAsCanvas(boolean print) {
    	// create canvas to draw circuit into
    	Canvas cv = Canvas.createIfSupported();
    	Rectangle bounds = getCircuitBounds();
    	
	// add some space on edges because bounds calculation is not perfect
    	int wmargin = 140;
    	int hmargin = 100;
    	int w = (bounds.width+wmargin) ;
    	int h = (bounds.height+hmargin) ;
    	cv.setCoordinateSpaceWidth(w);
    	cv.setCoordinateSpaceHeight(h);
    	double oldTransform[] = Arrays.copyOf(transform, 6);
    
	Context2d context = cv.getContext2d();
	Graphics g = new Graphics(context);
	context.setTransform(1, 0, 0, 1, 0, 0);
        
        double scale = 1;
        
	// turn on white background, turn off current display
	boolean p = printableCheckItem.getState();
	boolean c = dotsCheckItem.getState();
	if (print)
	    printableCheckItem.setState(true);
        if (printableCheckItem.getState()) {
            CircuitElm.whiteColor = Color.black;
            CircuitElm.lightGrayColor = Color.black;
            g.setColor(Color.white);
        } else {
            CircuitElm.whiteColor = Color.white;
            CircuitElm.lightGrayColor = Color.lightGray;
            g.setColor(Color.black);
            g.fillRect(0, 0, g.context.getCanvas().getWidth(), g.context.getCanvas().getHeight());
        }
	dotsCheckItem.setState(false);

        if (bounds != null)
            scale = Math.min(w /(double)(bounds.width+wmargin),
                             h/(double)(bounds.height+hmargin));
        scale = Math.min(scale, 1.5); // Limit scale so we don't create enormous circuits in big windows
        
        // ScopeElms need the transform array to be updated
	transform[0] = transform[3] = scale;
	transform[4] = -(bounds.x-wmargin/2);
	transform[5] = -(bounds.y-hmargin/2);
	context.scale(scale, scale);
	context.translate(transform[4], transform[5]);
	
	// draw elements
	int i;
	for (i = 0; i != elmList.size(); i++) {
	    getElm(i).draw(g);
	}
	
	// restore everything
	printableCheckItem.setState(p);
	dotsCheckItem.setState(c);
	transform = oldTransform;
	return cv;
}
 

public void onModuleLoad() {
	
	Canvas canvas = Canvas.createIfSupported();
	canvas.setStyleName("MyCanvas");
	canvas.setCoordinateSpaceWidth(400);
	canvas.setCoordinateSpaceHeight(400);
	RootLayoutPanel.get().add(canvas);
	
	gl = (WebGLRenderingContext)canvas.getContext("experimental-webgl");
	gl.viewport(0, 0, 400, 400);
	
	WebGLBuffer vertexBuffer = gl.createBuffer();
	gl.bindBuffer(ARRAY_BUFFER, vertexBuffer);
	gl.bufferData(ARRAY_BUFFER, Float32Array.create(VERTICES), STATIC_DRAW);

	WebGLShader vertexShader = gl.createShader(VERTEX_SHADER);
	gl.shaderSource(vertexShader, VERTEX_SHADER_SOURCE);
	gl.compileShader(vertexShader);
	
	WebGLShader fragmentShader = gl.createShader(FRAGMENT_SHADER);
	gl.shaderSource(fragmentShader, FRAGMENT_SHADER_SOURCE);
	gl.compileShader(fragmentShader);
	
	program = gl.createProgram();
	gl.attachShader(program, vertexShader);
	gl.attachShader(program, fragmentShader);
	gl.linkProgram(program);
	
	gl.useProgram(program);
	gl.bindBuffer(ARRAY_BUFFER, vertexBuffer);
	
	WebGLUniformLocation texture = gl.getUniformLocation(program, "texture");
	gl.uniform1i(texture, 0);
	
	int posAttr = gl.getAttribLocation(program, "position");
	gl.vertexAttribPointer(posAttr, 3, FLOAT, false, 5*4, 0);
	gl.enableVertexAttribArray(posAttr);
	
	int texAttr = gl.getAttribLocation(program, "texcoord");
	gl.vertexAttribPointer(texAttr, 2, FLOAT, false, 5*4, 3*4);
	gl.enableVertexAttribArray(texAttr);
	
	for(int i=0; i<TEXTURE_URLS.length; i++) {
		loadTexture(TEXTURE_URLS[i], i);
	}
	
}
 

public static Canvas createScaledCanvas(int width, int height) {
  Canvas canvas = Canvas.createIfSupported();
  
  scaleCanvas(canvas, width, height);

  return canvas;
}