android - 以编程方式创建一个带有渐变笔触的按钮？

Question

我正在创建一个没有填充但有渐变笔触的按钮。作为引用，这是我追求的最终结果:



我想知道如何以编程方式创建具有渐变笔触且无填充的按钮。我看了看GradientDrawable类和 setStroke()里面的方法。似乎没有人允许这样做。有没有办法以编程方式执行此操作，或者根本不可能？

Answer 1

我已经为你尝试了一些东西..
使用mRect.set设置路径和mPath.addRoundRect添加矩形。使用 setShader用于打击目的link

可绘制类:

public class CustomDrawable extends Drawable {
Paint mPaint;
int startColor, endColor, mBorderWidth, mBorderRadius;
RectF mRect;
Path mPath;

public CustomDrawable(int startColor, int endColor, int borderWidth, int borderRadius) {
    mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    mPaint.setStyle(Paint.Style.FILL);

    mPath = new Path();
    mPath.setFillType(Path.FillType.EVEN_ODD);

    mRect = new RectF();
    this.startColor = startColor;
    this.endColor = endColor;

    mBorderWidth = borderWidth;
    mBorderRadius = borderRadius;
}

@Override
protected void onBoundsChange(Rect bounds) {
    super.onBoundsChange(bounds);
    mPath.reset();

    // out rect
    mRect.set(bounds.left + mBorderWidth, bounds.top + mBorderWidth, bounds.right - mBorderWidth, bounds.bottom - mBorderWidth);
    mPath.addRoundRect(mRect, mBorderRadius, mBorderRadius, Path.Direction.CW);

    // inner rect
    mRect.set(bounds.left + 20, bounds.top + 20, bounds.right - 20, bounds.bottom - 20);
    mPath.addRoundRect(mRect, mBorderRadius, mBorderRadius, Path.Direction.CW);
}

@Override
public void draw(@NonNull Canvas canvas) {
    // kind of strock 
    mPaint.setShader(new LinearGradient(0, 0, 0, 100, startColor, endColor, Shader.TileMode.MIRROR));
    canvas.drawPath(mPath, 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;}
}

主要的 :

Button but = ((Button)findViewById(R.id.but));
but.setBackground(new CustomDrawable(Color.parseColor("#FD659B"),
       Color.parseColor("#F76E63"),
       but.getPaddingLeft(), 100));

布局 :

<Button
    android:id="@+id/but"
    android:layout_width="300dp"
    android:layout_height="80dp"
    android:background="@android:color/transparent"
    android:layout_centerInParent="true"
    android:text="Signin"/>