如果您只想进行位图处理（而不是 3D 或矢量），您最好的选择可能是：
- 从你的拼图中生成一个模板面具，
- 使用高斯差分对其进行处理（在本例中我使用大小为 12 和 2 像素的内核），然后对结果进行归一化和反转，
- 使用掩码 (1.) 作为模板通道，将“2”的输出 Alpha 混合到原始图像中。
更新：代码来了。我试图重用你的变量名，以便更容易理解。代码尽可能使用 Renderscript 内在函数，以使事情变得更快、更有趣。
private Paint fillPaint = null;
private Path path2;
private Bitmap mBitmapIn;
private Bitmap mBitmapPuzzle;
private RenderScript mRS;
private Allocation mInAllocation;
private Allocation mPuzzleAllocation;
private Allocation mCutterAllocation;
private Allocation mOutAllocation;
private Allocation mOutAllocation2;
private Allocation mAllocationHist;
private ScriptIntrinsicBlur mScriptBlur;
private ScriptIntrinsicBlend mScriptBlend;
private ScriptIntrinsicHistogram mScriptHistogram;
private ScriptIntrinsicLUT mScriptLUT;
private Context ctx;
private int bw = 780;
private int bh = 780;
private void init()
{
mBitmapIn = loadBitmap(R.drawable.cat7); // background image
mBitmapPuzzle = Bitmap.createBitmap(bw, bh, Bitmap.Config.ARGB_8888); // this will hold the puzzle
Canvas c = new Canvas(mBitmapPuzzle);
path2 = new Path();
createPath(5); // create the path with stroke width of 5 pixels
c.drawPath(path2, fillPaint); // draw it on canvas
createScript(); // get renderscripts and Allocations ready
// Apply gaussian blur of radius 25 to our drawing
mScriptBlur.setRadius(25);
mScriptBlur.setInput(mPuzzleAllocation);
mScriptBlur.forEach(mOutAllocation);
// Now apply the blur of radius 1
mScriptBlur.setRadius(1);
mScriptBlur.setInput(mPuzzleAllocation);
mScriptBlur.forEach(mOutAllocation2);
// Subtract one blur result from another
mScriptBlend.forEachSubtract(mOutAllocation, mOutAllocation2);
// We now want to normalize the result (e.g. make it use full 0-255 range).
// To do that, we will first compute the histogram of our image
mScriptHistogram.setOutput(mAllocationHist);
mScriptHistogram.forEach(mOutAllocation2);
// copy the histogram to Java array...
int []hist = new int[256 * 4];
mAllocationHist.copyTo(hist);
// ...and walk it from the end looking for the first non empty bin
int i;
for(i = 255; i > 1; i--)
if((hist[i * 4] | hist[i * 4 + 1] | hist[i * 4 + 2]) != 0)
break;
// Now setup the LUTs that will map the image to the new, wider range.
// We also use the opportunity to inverse the image ("255 -").
for(int x = 0; x <= i; x++)
{
int val = 255 - x * 255 / i;
mScriptLUT.setAlpha(x, 255); // note we always make it fully opaque
mScriptLUT.setRed(x, val);
mScriptLUT.setGreen(x, val);
mScriptLUT.setBlue(x, val);
}
// the mapping itself.
mScriptLUT.forEach(mOutAllocation2, mOutAllocation);
让我们休息一下，看看到目前为止我们有什么。观察左边的整个图像是不透明的（即包括拼图之外的空间），我们现在必须适当地切割形状并消除其边缘。不幸的是，使用原始形状是行不通的，因为它太大并且切割太多，导致边缘附近出现令人不快的伪影（右图）。
因此，我们绘制了另一条路径，这次使用的是更窄的笔划……
Bitmap mBitmapCutter = Bitmap.createBitmap(bw, bh, Bitmap.Config.ARGB_8888);
c = new Canvas(mBitmapCutter);
path2 = new Path();
createPath(1); // stroke width 1
c.drawPath(path2, fillPaint);
mCutterAllocation = Allocation.createFromBitmap(mRS, mBitmapCutter);
// cookie cutter now
mScriptBlend.forEachDstIn(mCutterAllocation, mOutAllocation);
...为了更好看的结果。让我们用它来掩盖背景图像。
mScriptBlend.forEachMultiply(mOutAllocation, mInAllocation);
mInAllocation.copyTo(mBitmapPuzzle);
}
你好呀！现在只是 Renderscript 设置代码。
private void createScript() {
mRS = RenderScript.create(ctx);
mPuzzleAllocation = Allocation.createFromBitmap(mRS, mBitmapPuzzle);
// three following allocations could actually use createSized(),
// but the code would be longer.
mInAllocation = Allocation.createFromBitmap(mRS, mBitmapIn);
mOutAllocation = Allocation.createFromBitmap(mRS, mBitmapPuzzle);
mOutAllocation2 = Allocation.createFromBitmap(mRS, mBitmapPuzzle);
mAllocationHist = Allocation.createSized(mRS, Element.I32_3(mRS), 256);
mScriptBlur = ScriptIntrinsicBlur.create(mRS, Element.U8_4(mRS));
mScriptBlend = ScriptIntrinsicBlend.create(mRS, Element.U8_4(mRS));
mScriptHistogram = ScriptIntrinsicHistogram.create(mRS, Element.U8_4(mRS));
mScriptLUT = ScriptIntrinsicLUT.create(mRS, Element.U8_4(mRS));
}
最后onDraw()：
@Override
protected void onDraw(Canvas canvas) {
canvas.drawBitmap(mBitmapPuzzle, 0, 0, fillPaint);
super.onDraw(canvas);
}
TODO：检查其他中风斜接是否会提供更舒适的角落。
