如何在启用了抗锯齿的情况下创建内存中完全透明的SWT图像并在其上绘制黑线?
我希望结果只包括黑色和alpha值,范围从0到255,因为抗锯齿......
我用谷歌搜索并尝试了所有我能做到的......这有可能吗?
答案 0 :(得分:4)
这就是我的方式,它起作用:
Image src = new Image(null, 16, 16);
ImageData imageData = src.getImageData();
imageData.transparentPixel = imageData.getPixel(0, 0);
src.dispose();
Image icon = new Image(null, imageData);
//draw on the icon with gc
答案 1 :(得分:3)
我是通过分配ImageData
来实现的,使其透明,然后从数据中创建Image
:
static Image createTransparentImage(Display display, int width, int height) {
// allocate an image data
ImageData imData = new ImageData(width, height, 24, new PaletteData(0xff0000,0x00ff00, 0x0000ff));
imData.setAlpha(0, 0, 0); // just to force alpha array allocation with the right size
Arrays.fill(imData.alphaData, (byte) 0); // set whole image as transparent
// Initialize image from transparent image data
return new Image(display, imData);
}
答案 2 :(得分:2)
我能够完成这项工作,虽然感觉有点笨拙:
Display display = Display.getDefault();
int width = 10;
int height = 10;
Image canvas = new Image(display, width, height);
GC gc = new GC(canvas);
gc.setAntialias(SWT.ON);
// This sets the alpha on the entire canvas to transparent
gc.setAlpha(0);
gc.fillRectangle(0, 0, width, height);
// Reset our alpha and draw a line
gc.setAlpha(255);
gc.setForeground(display.getSystemColor(SWT.COLOR_BLACK));
gc.drawLine(0, 0, width, height);
// We're done with the GC, so dispose of it
gc.dispose();
ImageData canvasData = canvas.getImageData();
canvasData.alphaData = new byte[width * height];
// This is the hacky bit that is making assumptions about
// the underlying ImageData. In my case it is 32 bit data
// so every 4th byte in the data array is the alpha for that
// pixel...
for (int idx = 0; idx < (width * height); idx++) {
int coord = (idx * 4) + 3;
canvasData.alphaData[idx] = canvasData.data[coord];
}
// Now that we've set the alphaData, we can create our
// final image
Image finalImage = new Image(canvasData);
// And get rid of the canvas
canvas.dispose();
在此之后,可以使用finalImage
将GC
绘制到drawImage
中,并且会尊重透明部分。
答案 3 :(得分:0)
为了透明地扩展,我发现我必须手动设置alpha字节数组,如下所示。所以alpha最终会得到最近邻抗锯齿。
public static Image scaleImage(Device device, Image orig, int scaledWidth, int scaledHeight) {
Rectangle origBounds = orig.getBounds();
if (origBounds.width == scaledWidth && origBounds.height == scaledHeight) {
return orig;
}
ImageData origData = orig.getImageData();
ImageData imData = new ImageData(scaledWidth, scaledHeight, origData.depth, origData.palette);
if (origData.alphaData != null) {
imData.alphaData = new byte[imData.width * imData.height];
for (int row = 0; row < imData.height; row++) {
for (int col = 0; col < imData.width; col++) {
int origRow = row * origData.height / imData.height;
int origCol = col * origData.width / imData.width;
byte origAlpha = origData.alphaData[origRow * origData.width + origCol];
imData.alphaData[row * imData.width + col] = origAlpha;
}
}
}
final Image scaled = new Image(device, imData);
GC gc = new GC(scaled);
gc.setAntialias(SWT.ON);
gc.setInterpolation(SWT.HIGH);
gc.setBackground(device.getSystemColor(SWT.COLOR_WHITE));
gc.fillRectangle(0, 0, scaledWidth, scaledHeight);
gc.drawImage(orig, 0, 0, origBounds.width, origBounds.height, 0, 0, scaledWidth, scaledHeight);
gc.dispose();
return scaled;
}