LinearGradientDrawable

import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.ColorFilter;
import android.graphics.LinearGradient;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.graphics.RectF;
import android.graphics.Shader;
import android.graphics.drawable.Drawable;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;

/**
 * 三种颜色渐变圆角drawable
 */
public class LinearGradientDrawable extends Drawable {

    private Paint mPaint;
    private int startColor = Color.parseColor("#f31c79");
    private int centerColor = Color.parseColor("#ff00c3");
    private int endColor = Color.parseColor("#b30c0c0c");
    private float progress;

    LinearGradientDrawable(int startColor, int centerColor, int endColor) {
        this();
        this.startColor = startColor;
        this.centerColor = centerColor;
        this.endColor = endColor;
    }

    LinearGradientDrawable() {
        mPaint = new Paint();
    }

    void updateProgress(float progress) {
        this.progress = progress;
        invalidateSelf();
    }

    @Override
    public void draw(@NonNull Canvas canvas) {
        mPaint.reset();
        if (startColor != endColor) {
            LinearGradient linearGradient = new LinearGradient(0, 0, getBounds().width(), 0,
                    new int[]{startColor, centerColor, endColor},
                    new float[]{progress * 0.5f, progress, progress - 0.01f}, Shader.TileMode.CLAMP);
            mPaint.setShader(linearGradient);
        } else {
            mPaint.setColor(startColor);
        }
        RectF rectF = new RectF(0, 0, getBounds().width(), getBounds().height());
        canvas.drawRoundRect(rectF, getBounds().height() / 2f, getBounds().height() / 2f, mPaint);
    }

    @Override
    public void setAlpha(int alpha) {
        mPaint.setAlpha(alpha);
    }

    @Override
    public void setColorFilter(@Nullable ColorFilter colorFilter) {
        mPaint.setColorFilter(colorFilter);
    }

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

}