我又来了一个机器人大脑的想法！
我想在图像视图中放置一个圆孔孔，该位图缩放为中心裁剪。我知道我需要在哪里放置圆孔（从左边和底部的dp）和孔半径。但是不知道如何构建它！
我知道我可以用波特达夫来打洞，但你建议怎么做？
- 自定义位图
- 自定义可绘制对象/视图
- 自定义代码
谢谢
以下答案是我的带孔的自定义图像：
public class MyImageView extends ImageView {
private AttributeSet attrs;
private float y;
private float x;
private float r;
private Paint paint;
private Rect mSrcRect;
private Rect mDestRect;
private Bitmap mBitmap;
private int alreadycalled = 0;
public MyImageView(Context context, AttributeSet attrs) {
super(context, attrs);
this.attrs = attrs;
initView();
}
public MyImageView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
this.attrs = attrs;
initView();
}
public MyImageView(Context context, float x, float y, float radius) {
super(context);
this.x = x;
this.y = y;
this.r = radius;
Log.d("parameters", String.format("left:%s , right:%s, radius:%s", String.valueOf(x), String.valueOf(y), String.valueOf(r)));
initView();
}
private void initView() {
paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setStyle(Paint.Style.FILL_AND_STROKE);
paint.setStrokeWidth(10);
paint.setColor(0xff000000);
}
@Override
protected void onDraw(Canvas canvas) {
alreadycalled++;
Log.d("alreadycalled", "called " + alreadycalled);
Drawable mDrawable = getDrawable();
if (mDrawable == null) {
return; // couldn't resolve the URI
}
int dWidth = mDrawable.getIntrinsicWidth();
int dHeight = mDrawable.getIntrinsicHeight();
float scale = 1.0f;
scale = Math.max(getWidth() * 1.0f / dWidth, getHeight()
* 1.0f / dHeight);
int nWidth = (int) (dWidth * scale);
int nHeight = (int) (dHeight * scale);
int offsetLeft = (nWidth - getWidth()) / 2;
int offsetTop = (nHeight - getHeight()) / 2;
mBitmap = ((BitmapDrawable) mDrawable).getBitmap();
//custom mSrcRect mDestRect to achieve centerCrop
mSrcRect = new Rect(0, 0, dWidth, dWidth);
mDestRect = new Rect(-offsetLeft, -offsetTop, getWidth() + offsetLeft, getHeight() + offsetTop);
Log.d("src", mSrcRect.toString());
Log.d("dest", mDestRect.toString());
int sc = canvas.saveLayer(0, 0, getWidth(), getHeight(), null,
Canvas.MATRIX_SAVE_FLAG | Canvas.CLIP_SAVE_FLAG
| Canvas.HAS_ALPHA_LAYER_SAVE_FLAG
| Canvas.FULL_COLOR_LAYER_SAVE_FLAG
| Canvas.CLIP_TO_LAYER_SAVE_FLAG);
paint.setColor(0xffffffff);
canvas.drawBitmap(mBitmap, mSrcRect, mDestRect, paint);
paint.setColor(0xffff0000);
paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_OUT));
Log.d("position", String.format("%s , %s", String.valueOf(x), String.valueOf(y)));
canvas.drawCircle(x, y, r, paint);
paint.setXfermode(null);
canvas.restoreToCount(sc);
}
我用这些行以编程方式调用它：
BitmapDrawable bd=(BitmapDrawable) getResources().getDrawable(R.drawable.triangle_bas_accueil2);
MyImageView customImView = new MyImageView(getApplicationContext(), mX, mY, mRadius);
customImView.setImageDrawable(bd);
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);
params.gravity = Gravity.BOTTOM;
customImView.setLayoutParams(params);
down_relative.addView(customImView);
但是onDraw()方法被调用了两次（也许它需要），但这让我有两个洞，一个我可以更改参数，但另一个仍然在同一个地方！ MyImageView的容器是一个RelativeLayout。
如果有人有想法？@tiny阳光 ？
这个只适用于 CenterCrop，不能处理 scaleType。而且这段代码可能会有一些问题，因为我不擅长画布。
public class MyImageView extends ImageView {
private final AttributeSet attrs;
private Paint paint;
private Rect mSrcRect;
private Rect mDestRect;
private Bitmap mBitmap;
public MyImageView(Context context, AttributeSet attrs) {
super(context, attrs);
this.attrs = attrs;
initView();
}
public MyImageView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
this.attrs = attrs;
initView();
}
private void initView() {
paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setStyle(Paint.Style.FILL_AND_STROKE);
paint.setStrokeWidth(10);
paint.setColor(0xff000000);
}
@Override
protected void onDraw(Canvas canvas) {
// super.onDraw(canvas);
//create the drawable.Maybe you can cache it.
Drawable mDrawable = (BitmapDrawable) getResources().getDrawable(R.drawable.triangle_bas_accueil2);
if (mDrawable == null) {
return; // couldn't resolve the URI
}
int dWidth = mDrawable.getIntrinsicWidth();
int dHeight = mDrawable.getIntrinsicHeight();
float scale = 1.0f;
scale = Math.max(getWidth() * 1.0f / dWidth, getHeight()
* 1.0f / dHeight);
int nWidth = (int) (dWidth*scale);
int nHeight = (int) (dHeight*scale);
int offsetLeft = (nWidth - getWidth())/2;
int offsetTop = (nHeight - getHeight())/2;
//cache mBitmap
mBitmap = mBitmap == null ? ((BitmapDrawable) mDrawable).getBitmap(): mBitmap;
//custom mSrcRect mDestRect to achieve centerCrop
mSrcRect = new Rect(0, 0, dWidth, dWidth);
mDestRect = new Rect(-offsetLeft, -offsetTop,getWidth()+offsetLeft, getHeight()+offsetTop);
int x = 250;int r = 100;
int sc = canvas.saveLayer(0, 0, getWidth(), getHeight(), null,
Canvas.MATRIX_SAVE_FLAG | Canvas.CLIP_SAVE_FLAG
| Canvas.HAS_ALPHA_LAYER_SAVE_FLAG
| Canvas.FULL_COLOR_LAYER_SAVE_FLAG
| Canvas.CLIP_TO_LAYER_SAVE_FLAG);
paint.setColor(0xffffffff);
canvas.drawBitmap(mBitmap,mSrcRect,mDestRect,paint);
paint.setColor(0xff000000);
paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_OUT));
canvas.drawCircle(x,x,r,paint);
paint.setXfermode(null);
canvas.restoreToCount(sc);
}
}
自定义代码。遍历每个像素并更改 Alpha。下面是一些伪代码：
for (int y = 0; y < imageHeight; y++) {
for (int x = 0; x < imageWidth; x++) {
// Check if the current pixel is within the circle
if (dist(x, y, centerX, centerY) <= radius) {
// Change the alpha
image.setPixelAlpha(x, y, 0);
}
}
}