好的,我需要裁剪特定形状的 ImageView,我不能通过添加 png 来做到这一点,因为背景可以是可变的(例如图案)。因此,我需要形状外部的区域是透明的。
形状必须是这样的:
我想用 Path() 来绘制这个形状并用它来遮盖 ImageView,但我完全不知道如何用 Path() 绘制这样的复杂形状。
非常感谢。
最佳答案
所以我很无聊,这看起来很有趣,所以我拼凑了一个简单的 Drawable,你可以用它来做这件事。您可以变得更漂亮并向其添加笔触和诸如此类的东西,但这适用于您建议的基本情况,并允许您将箭头设置为指向任何角落,并且还会缩放图像以适合边界可绘制的。结果如下:
您可以通过以下方式使用它:
BubbleDrawable bubbleDrawable = new BubbleDrawable(
this, R.drawable.your_image, BubbleDrawable.Corner.TOP_RIGHT);
myImageView.setImageDrawable(bubbleDrawable);
下面是 BubbleDrawable 的代码:
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.ColorFilter;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.Rect;
import android.graphics.RectF;
import android.graphics.Shader;
import android.graphics.drawable.Drawable;
import static android.graphics.Matrix.ScaleToFit.FILL;
import static android.graphics.Paint.ANTI_ALIAS_FLAG;
import static android.graphics.Path.Direction.CW;
import static android.graphics.PixelFormat.TRANSPARENT;
import static android.graphics.Shader.TileMode.CLAMP;
import static test.com.testrotationanimation.BubbleDrawable.Corner.TOP_LEFT;
public final class BubbleDrawable extends Drawable {
private final Matrix mMatrix = new Matrix();
private final Paint mPaint = new Paint(ANTI_ALIAS_FLAG);
private final Path mPath = new Path();
private final RectF mSrcRect = new RectF();
private final RectF mDstRect = new RectF();
private final Shader mShader;
private Corner mArrowCorner = TOP_LEFT;
public BubbleDrawable(Bitmap bitmap, Corner arrowCorner) {
// Initialize a BitmapShader with the image you wish to draw
// (you can use other TileModes like REPEAT or MIRROR if you prefer)
mShader = new BitmapShader(bitmap, CLAMP, CLAMP);
mPaint.setShader(mShader);
// Save the bounds of the bitmap as the src rectangle -- will
// be used later to update the matrix when the bounds change
// so that the image fits within the bounds of this drawable
mSrcRect.set(0, 0, bitmap.getWidth(), bitmap.getHeight());
// Set the corner in which the arrow will be drawn
mArrowCorner = arrowCorner;
}
public BubbleDrawable(Context ctx, int drawableResource, Corner arrowCorner) {
this(BitmapFactory.decodeResource(ctx.getResources(), drawableResource), arrowCorner);
}
public Corner getArrowCorner() {
return mArrowCorner;
}
public void setArrowCorner(Corner corner) {
mArrowCorner = corner;
updatePath();
invalidateSelf();
}
@Override
protected void onBoundsChange(Rect bounds) {
super.onBoundsChange(bounds);
updateMatrix(bounds);
updatePath();
}
private void updateMatrix(Rect bounds) {
// Set the destination rectangle for the bitmap to be the
// new drawable bounds
mDstRect.set(bounds);
// Scale the bitmap's rectangle to the bounds of this drawable
mMatrix.setRectToRect(mSrcRect, mDstRect, FILL);
// Update the shader's matrix (to draw the bitmap at the right size)
mShader.setLocalMatrix(mMatrix);
}
private void updatePath() {
final Rect bounds = getBounds();
final float x = bounds.exactCenterX();
final float y = bounds.exactCenterY();
// Draw the initial circle (same for all corners)
mPath.reset();
mPath.addCircle(x, y, Math.min(x, y), CW);
// Add the rectangle which intersects with the center,
// based on the corner in which the arrow should draw
switch (mArrowCorner) {
case TOP_LEFT:
mPath.addRect(bounds.left, bounds.top, x, y, CW);
break;
case TOP_RIGHT:
mPath.addRect(x, bounds.top, bounds.right, y, CW);
break;
case BOTTOM_LEFT:
mPath.addRect(bounds.left, y, x, bounds.bottom, CW);
break;
case BOTTOM_RIGHT:
mPath.addRect(x, y, bounds.right, bounds.bottom, CW);
break;
}
}
@Override
public void draw(Canvas canvas) {
// Easy enough, just draw the path using the paint.
// It already has the BitmapShader applied which
// will do the work for you.
canvas.drawPath(mPath, mPaint);
}
@Override
public int getOpacity() {
// Indicate that this Drawable has fully-transparent pixel values
return TRANSPARENT;
}
@Override
public void setColorFilter(ColorFilter colorFilter) {
// Yay, you can even support color filters for your drawable
mPaint.setColorFilter(colorFilter);
}
@Override
public void setAlpha(int i) {
// You could do this by doing some canvas magic but I'm
// lazy and don't feel like it. Exercise for the reader. :)
throw new UnsupportedOperationException("Not implemented.");
}
public enum Corner {
TOP_LEFT, TOP_RIGHT, BOTTOM_LEFT, BOTTOM_RIGHT
}
}
关于java - 设计用于裁剪 ImageView 的路径,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/25109963/