android 方式实现 imageview 圆角

public static final int TYPE_ROUND = 1;

/**

• 圆角大小的默认值

*/

private static final int BODER_RADIUS_DEFAULT = 10;

/**

• 圆角的大小

*/

private int mBorderRadius;

/**

• 绘图的 Paint

*/

private Paint mBitmapPaint;

/**

• 圆角的半径

*/

private int mRadius;

/**

• 3x3 矩阵，主要用于缩小放大

*/

private Matrix mMatrix;

/**

• 渲染图像，使用图像为绘制图形着色

*/

private BitmapShader mBitmapShader;

/**

• view 的宽度

*/

private int mWidth;

private RectF mRoundRect;

/**

• 构造函数:获取自定义属性

*/

public RoundImageView(Context context, AttributeSet attrs) {

super(context, attrs);

mMatrix = new Matrix();

mBitmapPaint = new Paint();

mBitmapPaint.setAntiAlias(true);

TypedArray a = context.obtainStyledAttributes(attrs,

R.styleable.RoundImageView);

mBorderRadius = a.getDimensionPixelSize(

R.styleable.RoundImageView_borderRadius, (int) TypedValue

.applyDimension(TypedValue.COMPLEX_UNIT_DIP,

BODER_RADIUS_DEFAULT, getResources()

.getDisplayMetrics()));// 默认为 10dp

type = a.getInt(R.styleable.RoundImageView_type, TYPE_CIRCLE);// 默认为 Circle

a.recycle();

}

/**

• 关于 view 的宽高:主要用于当设置类型为圆形时，我们强制让 view 的宽和高一致

*/

@Override

protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

Log.e("TAG", "onMeasure");

super.onMeasure(widthMeasureSpec, heightMeasureSpec);

/**

• 如果类型是圆形，则强制改变 view 的宽高一致，以小值为准;如果是圆角则不用管宽高问题

*/

if (type == TYPE_CIRCLE) {

mWidth = Math.min(getMeasuredWidth(), getMeasuredHeight());

mRadius = mWidth / 2;

setMeasuredDimension(mWidth, mWidth);

}

}

/**

• 设置 BitmapShader

• 绘制

*/

@Override

protected void onDraw(Canvas canvas) {

if (getDrawable() == null) {

return;

}

setUpShader();

if (type == TYPE_ROUND) {

canvas.drawRoundRect(mRoundRect, mBorderRadius, mBorderRadius,

mBitmapPaint);

} else {

canvas.drawCircle(mRadius, mRadius, mRadius, mBitmapPaint);

// drawSomeThing(canvas);

}

}

@Override

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ted void onSizeChanged(int w, int h, int oldw, int oldh) {

super.onSizeChanged(w, h, oldw, oldh);

// 圆角图片的范围

if (type == TYPE_ROUND)

mRoundRect = new RectF(0, 0, getWidth(), getHeight());

}

/**

• 初始化 BitmapShader//给 paint 附加一个具有某种魔力(缩放)的 shader

• drawable 转化为我们的 bitmap

• 设置 shader 的 mode

• 设置 scale: 因为最终缩放完成的图片一定要大于我们的 view 的区域

• scale 设置给 matrix

• matrix 设置给 shader

• shader 设置给 paint

*/

private void setUpShader() {

Drawable drawable = getDrawable();

if (drawable == null) {

return;

}

Bitmap bmp = drawableToBitamp(drawable);

// 将 bmp 作为着色器，就是在指定区域内绘制 bmp;此构造方法用的是拉伸 mode: clamp

mBitmapShader = new BitmapShader(bmp, CLAMP, CLAMP);

float scale = 1.0f;

if (type == TYPE_CIRCLE) {

// 拿到 bitmap 宽或高的小值//我们需要画正方形

int bSize = Math.min(bmp.getWidth(), bmp.getHeight());

scale = mWidth * 1.0f / bSize;

} else if (type == TYPE_ROUND) {

// 如果图片的宽或者高与 view 的宽高不匹配，计算出需要缩放的比例；缩放后的图片的宽高，一定要大于我们 view 的宽高；所以我们这里取大值；//view 的宽度/bitmap 的宽度=缩放倍数

scale = Math.max(getWidth() * 1.0f / bmp.getWidth(), getHeight()

• 1.0f / bmp.getHeight());

}

// shader 的变换矩阵，我们这里主要用于放大或者缩小

mMatrix.setScale(scale, scale);

// 设置变换矩阵

mBitmapShader.setLocalMatrix(mMatrix);

// 先给 paint 设置 shader;然后画笔会有所不同哦,例如

mBitmapPaint.setShader(mBitmapShader);

}

/**

• drawable 转 bitmap

• @param drawable

• @return

*/

private Bitmap drawableToBitamp(Drawable drawable) {

if (drawable instanceof BitmapDrawable) {

BitmapDrawable bd = (BitmapDrawable) drawable;

return bd.getBitmap();

}

//以下为 drawable 转 bitmap 的通用方法

int w = drawable.getIntrinsicWidth();

int h = drawable.getIntrinsicHeight();

Bitmap bitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);

Canvas canvas = new Canvas(bitmap);

drawable.setBounds(0, 0, w, h);

drawable.draw(canvas);

return bitmap;

}

/**

• 添加一个方法

• bitmap 转 drawable

*/

private Drawable bitmapToDrawable(Bitmap bitmap) {

Drawable drawable = new BitmapDrawable(null, bitmap);

return drawable;

}

//状态存储与恢复

private static final String STATE_INSTANCE = "state_instance";

private static final String STATE_TYPE = "state_type";

private static final String STATE_BORDER_RADIUS = "state_border_radius";

@Override

protected Parcelable onSaveInstanceState() {

Bundle bundle = new Bundle();

bundle.putParcelable(STATE_INSTANCE, super.onSaveInstanceState());

bundle.putInt(STATE_TYPE, type);

bundle.putInt(STATE_BORDER_RADIUS, mBorderRadius);

return bundle;

}

@Override

protected void onRestoreInstanceState(Parcelable state) {

if (state instanceof Bundle) {

Bundle bundle = (Bundle) state;

super.onRestoreInstanceState(((Bundle) state)

.getParcelable(STATE_INSTANCE));

this.type = bundle.getInt(STATE_TYPE);

this.mBorderRadius = bundle.getInt(STATE_BORDER_RADIUS);

} else {

super.onRestoreInstanceState(state);

}