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创建半圆背景,可使用透明

android-drawable android-layout android

BekaKK · 技术社区 · 7 年前

我写了代码,几乎可以正常工作

public class GetsugaDrawable extends Drawable {

private final Context context;
private final float radiusScale = 1.2f;
private final float yOffset = 0.3f;

private final int colorLower = Color.RED;
private final int colorUpper = Color.BLACK;

private final Paint upperPaint = new Paint();

public GetsugaDrawable(Context c) {
    context = c;
    upperPaint.setColor(colorUpper);
    upperPaint.setFlags(Paint.ANTI_ALIAS_FLAG);
}

@Override
public void draw(@NonNull Canvas canvas) {
    final Rect bounds = new Rect(getBounds());
    canvas.drawColor(colorLower, PorterDuff.Mode.SRC);
    final float radius = radiusScale * bounds.height();
    final int x = bounds.centerX();
    final float y = (bounds.centerY() - bounds.height() * yOffset) - radius;
    canvas.drawCircle(x, y, radius, upperPaint);
}

@Override
public void setAlpha(int alpha) {
    // ignored TODO impl.
}

@Override
public void setColorFilter(@Nullable ColorFilter colorFilter) {
    // ignored TODO impl.
}

@Override
public int getOpacity() {
    return PixelFormat.TRANSLUCENT;
}
}

我试着改变

    private final int colorUpper = Color.BLACK;

具有

    private final int colorUpper = Color.TRANSPARENT;

我做错了什么?

2 回复 | 直到 7 年前

Ravi Kant 7 年前

添加upperPaint。setXfermode(新的PorterDuffXfermode(PorterDuff.Mode.CLEAR));

public class GetsugaDrawable extends Drawable {
private final Context context;
private final float radiusScale = 1.2f;
private final float yOffset = 0.3f;

private final int colorLower = Color.RED;
private final int colorUpper = Color.BLACK;

private final Paint upperPaint = new Paint();

public GetsugaDrawable(Context c) {
    context = c;
    upperPaint.setAntiAlias(true);
    upperPaint.setColor(colorUpper);
    upperPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));      
}

@Override
public void draw(@NonNull Canvas canvas) {
    final Rect bounds = new Rect(getBounds());
    canvas.drawColor(colorLower);
    final float radius = radiusScale * bounds.height();
    final int x = bounds.centerX();
    final float y = (bounds.centerY() - bounds.height() * yOffset) - radius;
    canvas.drawCircle(x, y, radius, upperPaint);
}

@Override
public void setAlpha(int alpha) {

}

@Override
public void setColorFilter(@Nullable ColorFilter colorFilter) {

}

@Override
public int getOpacity() {
    return PixelFormat.TRANSLUCENT;
}}

不要忘记观看。setLayerType(View.LAYER\u TYPE\u HARDWARE,null);在目标视图上

amuyu 7 年前

你可以改变 draw 作用

@Override
public void draw(@NonNull Canvas canvas) {
    final Rect bounds = new Rect(getBounds());
    final float radius = radiusScale * bounds.height();
    final int x = bounds.centerX();
    final float y = (bounds.centerY() - bounds.height() * yOffset) - radius;
    Path path = new Path();
    path.addCircle(x, y, radius, CW);
    canvas.clipPath(path, Region.Op.DIFFERENCE);
    canvas.drawColor(colorLower);
}