Android开发之圆角矩形创建工具RoundRect类定义与用法分析

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.RectF;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
public class RoundRect {
private int width;
private int height;
private float cornerRadius;
/**
* 用于初始化圆角矩形基本参数
*
* @param width    图片宽度
* @param height    图片高度
* @param cornerRadius 圆角半径
*/
public RoundRect(int width, int height, float cornerRadius) {
this.width = width;
this.height = height;
this.cornerRadius = cornerRadius;
}
/**
* 用于把普通图片转换为圆角矩形图像
*
* @param path 图片路径
* @return output 转换后的圆角矩形图像
*/
Bitmap toRoundRect(String path) {
//创建位图对象
Bitmap photo = lessenUriImage(path);
return Transformation(photo);
}
/**
* 用于把普通图片转换为圆角矩形图像
*
* @param imageID 图片资源ID
* @param context 上下文对象
* @return output 转换后的圆角矩形图像
*/
Bitmap toRoundRect(Context context, int imageID) {
//创建位图对象
Bitmap photo = BitmapFactory.decodeResource(context.getResources(), imageID);
return Transformation(photo);
}
/**
* 用于把Uri图片转换为Bitmap对象
*
* @param path 图片URI地址
* @return 生成的Bitmap对象
*/
public final static Bitmap lessenUriImage(String path) {
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
Bitmap bitmap = BitmapFactory.decodeFile(path, options); //此时返回 bm 为空
options.inJustDecodeBounds = false; //缩放比。由于是固定比例缩放，只用高或者宽其中一个数据进行计算即可
int be = (int) (options.outHeight / (float) 320);
if (be <= 0) be = 1;
options.inSampleSize = be; //重新读入图片，注意此时已经把 options.inJustDecodeBounds 设回 false 了
bitmap = BitmapFactory.decodeFile(path, options);
int w = bitmap.getWidth();
int h = bitmap.getHeight();
System.out.println(w + " " + h); //after zoom
return bitmap;
}
/**
* 用于把Bitmap图像转换为圆角图像
*
* @param photo 需要转换的Bitmap对象
* @return 转换成圆角的Bitmap对象
*/
private Bitmap Transformation(Bitmap photo) {
//根据源文件新建一个darwable对象
Drawable imageDrawable = new BitmapDrawable(photo);
// 新建一个新的输出图片
Bitmap output = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(output);
// 新建一个矩形
RectF outerRect = new RectF(0, 0, width, height);
// 产生一个红色的圆角矩形
Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setColor(Color.RED);
canvas.drawRoundRect(outerRect, cornerRadius, cornerRadius, paint);
// 将源图片绘制到这个圆角矩形上
paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
imageDrawable.setBounds(0, 0, width, height);
canvas.saveLayer(outerRect, paint, Canvas.ALL_SAVE_FLAG);
imageDrawable.draw(canvas);
canvas.restore();
return output;
}
}

public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.image);
ImageView image = (ImageView)findViewById(R.id.image);
RoundRect roundRect = new RoundRect(500,500,100);
Bitmap photo = roundRect.toRoundRect(this,R.drawable.kms);
image.setImageBitmap(photo);
}
}

public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.image);
ImageView image = (ImageView)findViewById(R.id.image);
RoundRect roundRect = new RoundRect(500,500,300);
Bitmap photo = roundRect.toRoundRect(this,R.drawable.indark);
image.setImageBitmap(photo);
}
}