一个圆角图片的解决方案，解决设计需要不同圆角图片时，避免重复让设计师出不一样的切图。
代码很简单，如果有需要，可以直接引用git项目
废话不多说，先上效果图：
圆角图形.jpg
属性介绍
| 参数 | 属性 | 介绍 |
|---|---|---|
| round_rect_circle | boolean | 是否显示圆形 |
| round_rect_corner | int | 圆角大小 |
| round_rect_corner_top_to_left | int | 左上角圆弧 |
| round_rect_corner_top_to_right | int | 右上角圆弧 |
| round_rect_corner_bottom_to_left | int | 左下角圆弧 |
| round_rect_corner_bottom_to_right | int | 右下角圆弧 |
| round_rect_stroke_color | int | 描边颜色 |
| round_rect_stroke_width | int | 描边大小 |
- round_rect_circle：默认false，如果是true，直接绘制圆形。
- round_rect_corner：四个角圆弧属性，默认为0。
- round_rect_corner_top_to_left：左上角圆弧，如果设置了该属性，round_rect_corner的左上角设置不起作用。
- round_rect_corner_top_to_right：右上角圆弧，如果设置了该属性，round_rect_corner的右上角设置不起作用。
- round_rect_corner_bottom_to_left：左下角圆弧，如果设置了该属性，round_rect_corner的左下角设置不起作用。
- round_rect_corner_bottom_to_right：右下角圆弧，如果设置了该属性，round_rect_corner的右下角设置不起作用。
- round_rect_stroke_color：描边的颜色，默认是白色。
- round_rect_stroke_width：圆弧的描边，默认描边的宽度是0。
实现思路
先上完整代码：
首先先定义圆角图形所需要的属性：
然后在定义一个RoundRectLayout继承RelativeLayout：完整代码如下：
ublic class RoundRectLayout extends RelativeLayout {
private RectF mRectF;//绘制画布的大小
public float[] mRadii = new float[8];//绘制眼角矩形所需的8个角
private boolean mCircle;//是否是绘制圆形
private int mRectCorner; //圆角弧度
private int mStrokeColor;// 描边颜色
private int mStrokeWidth;// 描边宽度
public RoundRectLayout(Context context) {
this(context, null);
}
public RoundRectLayout(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public RoundRectLayout(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
initView(context, attrs);
}
private void initView(Context context, AttributeSet attrs) {
TypedArray array = context.obtainStyledAttributes(attrs, R.styleable.RoundRectLayout);
mCircle = array.getBoolean(R.styleable.RoundRectLayout_round_rect_circle, false);
mRectCorner = array.getDimensionPixelSize(R.styleable.RoundRectLayout_round_rect_corner, 0);
int roundRectTopLeft = array.getDimensionPixelSize(R.styleable.RoundRectLayout_round_rect_corner_top_to_left, -1);
int roundRectTopRight = array.getDimensionPixelSize(R.styleable.RoundRectLayout_round_rect_corner_top_to_right, -1);
int roundRectBottomLeft = array.getDimensionPixelSize(R.styleable.RoundRectLayout_round_rect_corner_bottom_to_left, -1);
int roundRectBottomRight = array.getDimensionPixelSize(R.styleable.RoundRectLayout_round_rect_corner_bottom_to_right, -1);
mRadii[0] = roundRectTopLeft == -1 ? mRectCorner : roundRectTopLeft;
mRadii[1] = roundRectTopLeft == -1 ? mRectCorner : roundRectTopLeft;
mRadii[2] = roundRectTopRight == -1 ? mRectCorner : roundRectTopRight;
mRadii[3] = roundRectTopRight == -1 ? mRectCorner : roundRectTopRight;
mRadii[4] = roundRectBottomLeft == -1 ? mRectCorner : roundRectBottomLeft;
mRadii[5] = roundRectBottomLeft == -1 ? mRectCorner : roundRectBottomLeft;
mRadii[6] = roundRectBottomRight == -1 ? mRectCorner : roundRectBottomRight;
mRadii[7] = roundRectBottomRight == -1 ? mRectCorner : roundRectBottomRight;
mStrokeColor = array.getColor(R.styleable.RoundRectLayout_round_rect_stroke_color, Color.WHITE);
mStrokeWidth = array.getDimensionPixelSize(R.styleable.RoundRectLayout_round_rect_stroke_width, 0);
array.recycle();
mRectF = new RectF();
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
mRectF.left = getPaddingLeft();
mRectF.top = getPaddingTop();
mRectF.right = w - getPaddingRight();
mRectF.bottom = h - getPaddingBottom();
}
@Override
protected void dispatchDraw(Canvas canvas) {
canvas.saveLayer(mRectF, null, Canvas.ALL_SAVE_FLAG);
super.dispatchDraw(canvas);
Path path = new Path();
path.reset();
//判断是否绘制圆
if (mCircle) {
float width = (mRectF.right - mRectF.left) > (mRectF.bottom - mRectF.top) ? mRectF.bottom - mRectF.top : mRectF.right - mRectF.left;
path.addCircle((mRectF.right - mRectF.left) / 2, (mRectF.bottom - mRectF.top) / 2, (width - mStrokeWidth) / 2, Path.Direction.CW);
} else {
path.addRoundRect(mRectF, mRadii, Path.Direction.CW);
}
Paint paint = new Paint();
paint.setAntiAlias(true);
//绘制描边
if (mStrokeWidth > 0) {
paint.setColor(mStrokeColor);
paint.setStrokeWidth(mStrokeWidth);
paint.setStyle(Paint.Style.STROKE);
canvas.drawPath(path, paint);
}
//剪切圆角矩形
paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN));
paint.setStyle(Paint.Style.FILL);
canvas.drawPath(path, paint);
}
}
使用步骤
在xml文件直接引用
具体的实现思路：
首先要获取自定义的属性：
TypedArray array = context.obtainStyledAttributes(attrs, R.styleable.RoundRectLayout);
mCircle = array.getBoolean(R.styleable.RoundRectLayout_round_rect_circle, false);
mRectCorner = array.getDimensionPixelSize(R.styleable.RoundRectLayout_round_rect_corner, 0);
int roundRectTopLeft = array.getDimensionPixelSize(R.styleable.RoundRectLayout_round_rect_corner_top_to_left, -1);
int roundRectTopRight = array.getDimensionPixelSize(R.styleable.RoundRectLayout_round_rect_corner_top_to_right, -1);
int roundRectBottomLeft = array.getDimensionPixelSize(R.styleable.RoundRectLayout_round_rect_corner_bottom_to_left, -1);
int roundRectBottomRight = array.getDimensionPixelSize(R.styleable.RoundRectLayout_round_rect_corner_bottom_to_right, -1);
mRadii[0] = roundRectTopLeft == -1 ? mRectCorner : roundRectTopLeft;
mRadii[1] = roundRectTopLeft == -1 ? mRectCorner : roundRectTopLeft;
mRadii[2] = roundRectTopRight == -1 ? mRectCorner : roundRectTopRight;
mRadii[3] = roundRectTopRight == -1 ? mRectCorner : roundRectTopRight;
mRadii[4] = roundRectBottomLeft == -1 ? mRectCorner : roundRectBottomLeft;
mRadii[5] = roundRectBottomLeft == -1 ? mRectCorner : roundRectBottomLeft;
mRadii[6] = roundRectBottomRight == -1 ? mRectCorner : roundRectBottomRight;
mRadii[7] = roundRectBottomRight == -1 ? mRectCorner : roundRectBottomRight;
mStrokeColor = array.getColor(R.styleable.RoundRectLayout_round_rect_stroke_color, Color.WHITE);
mStrokeWidth = array.getDimensionPixelSize(R.styleable.RoundRectLayout_round_rect_stroke_width, 0);
array.recycle();
获取到之后要及时关闭typeArray，这个不需要详述，然后在onSizeChanged()方法中获取当前view的大小属性。onSizeChanged方法会在view有改动的时候调用，第一次创建view的时候也会调用一次。然后在dispatchDraw()方法中绘制图形。
因为要使用setXfermode方法，所以首先要进行离屏缓冲，至于为什么，请点击了解，行离屏缓冲很简单，只需要一行代码：
canvas.saveLayer(mRectF, null, Canvas.ALL_SAVE_FLAG);
然后判断是绘制圆形还是圆角矩形，绘制画布路径
Path path = new Path();
path.reset();
//判断是否绘制圆
if (mCircle) {
float width = (mRectF.right - mRectF.left) > (mRectF.bottom - mRectF.top) ? mRectF.bottom - mRectF.top : mRectF.right - mRectF.left;
path.addCircle((mRectF.right - mRectF.left) / 2, (mRectF.bottom - mRectF.top) / 2, (width - mStrokeWidth) / 2, Path.Direction.CW);
} else {
path.addRoundRect(mRectF, mRadii, Path.Direction.CW);
}
之后判断是否需要描边
//绘制描边
if (mStrokeWidth > 0) {
paint.setColor(mStrokeColor);
paint.setStrokeWidth(mStrokeWidth);
paint.setStyle(Paint.Style.STROKE);
canvas.drawPath(path, paint);
}
最后通过drawPath方法绘制需要的图形
//剪切圆角矩形
paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN));
paint.setStyle(Paint.Style.FILL);
canvas.drawPath(path, paint);