使用安卓自带的裁剪工具，发现有版本兼容问题，而且图片模糊问题也不好解决，于是自己动手绘制一个裁剪工具。先看效果!
最终效果
实现思路
- 打开本地相册，获得图片Uri，Uri转为Bitmap。
- 用自定义View绘制可拖动选框，获得用户的裁剪意图。
- 用Bitmap.createBitmap(bitmap,0,0,0,0,null,false);进行裁剪。
一、打开本地相册，获得图片Uri，Uri转为Bitmap。
- 首先是打开相册
Intent intent = new Intent();
intent.setAction(Intent.ACTION_PICK);
intent.setType("image/*");
intentActivityResultLauncher.launch(intent);
- 然后监听回调结果，onActivityResult被摒弃的事情不多说了，这里用registerForActivityResult。
private ActivityResultLauncher<Intent> intentActivityResultLauncher;
private void initActivityResult() {
intentActivityResultLauncher = registerForActivityResult(new ActivityResultContracts.StartActivityForResult(), result -> {
if (result.getResultCode() == RESULT_OK) {
Uri imageUri = Objects.requireNonNull(result.getData()).getData();
InputStream image_stream = null;
try {
image_stream = getContentResolver().openInputStream(imageUri);
Bitmap bitmap= BitmapFactory.decodeStream(image_stream );
//这里的bitmap就是我们要进行操作的位图，实现了第一步
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}
});
}
需要注意的是，这个东西一定要记得注销监听，不然会有内存泄露风险。
@Override
protected void onDestroy() {
super.onDestroy();
intentActivityResultLauncher.unregister();
}
2. 自定义View实现位图裁剪（直接copy去用，不需要考虑兼容性问题）
package com.example.cavasdemo;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Toast;
import androidx.annotation.Nullable;
/**
* 自定义View: Bitmap自定义裁剪工具
* @Author 绝命三郎
*/
public class BitmapClippingView extends View {
public BitmapClippingView(Context context) {
this(context,null);
}
public BitmapClippingView(Context context, @Nullable AttributeSet attrs) {
this(context, attrs,0);
}
public BitmapClippingView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
private float widthSize;//布局宽度
private float heightSize;//布局高度
private Bitmap bitmap;//要裁剪的位图
private float bitmapWidth;//位图原始宽度
private float bimapHeight;//位图原始高度
private float proportionWidth;//比例：宽 如裁图比例3:4，此处传3
private float proportionHeight;//比例：高 如裁图比例3:4，此处传4
private Paint bitmapPaint;//图片画笔
private Paint shadowPaint;//阴影画笔
private Paint linePaint;//线条画笔
float scaleStep;//缩放比例
private boolean initTag=true;//用于判断是不是首次绘制
private float leftLine=-1;//选区左线
private float topLine=-1;//选区上线
private float rightLine=-1;//选区右线
private float bottomLine=-1;//选区下线
private String focus="NONE";//事件焦点
private final String LEFT_TOP="LEFT_TOP";//LEFT_TOP:拖动左上角
private final String BODY="BODY";//BODY：拖动整体
private final String RIGHT_BOTTOM="RIGHT_BOTTOM";//RIGHT_BOTTOM:拖动右下角
private final String NONE="NONE";//NONE:释放焦点
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
widthSize=MeasureSpec.getSize(widthMeasureSpec);
heightSize=MeasureSpec.getSize(heightMeasureSpec);
bitmapPaint=new Paint();
bitmapPaint.setStrokeWidth(0);
shadowPaint=new Paint();
shadowPaint.setColor(Color.parseColor("#57FF9800"));
shadowPaint.setStrokeWidth(4);
shadowPaint.setStyle(Paint.Style.FILL_AND_STROKE);
linePaint=new Paint();
linePaint.setColor(Color.parseColor("#FF9800"));
linePaint.setStrokeWidth(4);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
if (bitmap==null)return;
//绘制参考背景背景
scaleStep=widthSize/bitmapWidth;
float backgroundImgHeight=bimapHeight*scaleStep;
heightSize=backgroundImgHeight;//把有效图像高度设置作为布局高度计算
Rect rect=new Rect(0,0,(int)bitmapWidth,(int)bimapHeight);//裁剪图片中的部分(此处：全图)
RectF rectF=new RectF(0,0,widthSize,backgroundImgHeight);//显示在屏幕中的什么位置
canvas.drawBitmap(bitmap,rect,rectF,bitmapPaint);
canvas.save();
if (initTag){
//绘制初始状态的选框（最大选框）
if (bitmapWidth>bimapHeight){
//宽大于高，取高
float checkboxHeight=backgroundImgHeight;//选框的高
float checkboxWidth=((checkboxHeight/proportionHeight)*proportionWidth);//选框的宽
leftLine=(widthSize/2f)-(checkboxWidth/2f);
topLine=(heightSize/2f)-(checkboxHeight/2f);
rightLine=(widthSize/2f)+(checkboxWidth/2f);
bottomLine=(heightSize/2f)+(checkboxHeight/2f);
}else {
//高大于宽 取宽
float checkboxWidth=widthSize;//选框的宽
float checkboxHeight=(widthSize/proportionWidth)*proportionHeight;//选框的高
leftLine=(widthSize/2f)-(checkboxWidth/2f);
topLine=(heightSize/2f)-(checkboxHeight/2f);
rightLine=(widthSize/2f)+(checkboxWidth/2f);
bottomLine=(heightSize/2f)+(checkboxHeight/2f);
}
initTag=false;
}
//绘制选择的区域
//绘制周边阴影部分（分四个方块）
linePaint.setColor(Color.parseColor("#FF9800"));
linePaint.setStrokeWidth(4);
canvas.drawRect(0,0,leftLine,heightSize,shadowPaint);//左
canvas.drawRect(leftLine+4,0,rightLine-4,topLine,shadowPaint);//上
canvas.drawRect(rightLine,0,widthSize,heightSize,shadowPaint);//右
canvas.drawRect(leftLine+4,bottomLine,rightLine-4,heightSize,shadowPaint);//下
//绘制选区边缘线
canvas.drawLine(leftLine,topLine,rightLine,topLine,linePaint);
canvas.drawLine(rightLine,topLine,rightLine,bottomLine,linePaint);
canvas.drawLine(rightLine,bottomLine,leftLine,bottomLine,linePaint);
canvas.drawLine(leftLine,bottomLine,leftLine,topLine,linePaint);
//绘制左上和右下调节点
linePaint.setColor(Color.RED);
linePaint.setStrokeWidth(6);
canvas.drawLine(rightLine-4,bottomLine-4,rightLine-4,bottomLine-40-4,linePaint);
canvas.drawLine(rightLine-4,bottomLine-4,rightLine-40-4,bottomLine-4,linePaint);
canvas.drawLine(leftLine+4,topLine+4,leftLine+40+4,topLine+4,linePaint);
canvas.drawLine(leftLine+4,topLine+4,leftLine+4,topLine+40+4,linePaint);
//绘制焦点圆
linePaint.setStrokeWidth(2);
linePaint.setStyle(Paint.Style.STROKE);
canvas.drawCircle(rightLine-4,bottomLine-4,80,linePaint);
canvas.drawCircle(leftLine+4,topLine+4,80,linePaint);
//绘制扇形
linePaint.setColor(Color.parseColor("#57FF0000"));
linePaint.setStyle(Paint.Style.FILL_AND_STROKE);
RectF mRectF = new RectF(rightLine-4-40, bottomLine-4-40, rightLine-4+40, bottomLine-4+40);
canvas.drawArc(mRectF, 270, 270, true, linePaint);
linePaint.setColor(Color.parseColor("#57FF0000"));
linePaint.setStyle(Paint.Style.FILL_AND_STROKE);
RectF mRectF2 = new RectF(leftLine+4-40, topLine+4-40, leftLine+4+40, topLine+4+40);
canvas.drawArc(mRectF2, 90, 270, true, linePaint);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
if (leftLine==-1)return false;
if (topLine==-1)return false;
if (rightLine==-1)return false;
if (bottomLine==-1)return false;
if (bitmap==null)return false;
float touchX=event.getX();
float touchY=event.getY();
if (event.getAction()==MotionEvent.ACTION_DOWN){
return actionDown(touchX,touchY);
}
if (event.getAction()==MotionEvent.ACTION_MOVE){
return actionMove(touchX,touchY);
}
if (event.getAction()==MotionEvent.ACTION_UP){
return actionUp(touchX,touchY);
}
return true;
}
//抬起
private boolean actionUp(float touchX, float touchY) {
Log.d("fxHou","抬起X="+touchX+" touchY="+touchY);
Log.d("fxHou","释放焦点");
focus=NONE;//释放焦点
return true;
}
//移动
private boolean actionMove(float touchX, float touchY) {
Log.d("fxHou","滑动X="+touchX+" touchY="+touchY);
if (focus.equals(LEFT_TOP)){
//移动边线
leftLine=touchX;
topLine=bottomLine-(((rightLine-leftLine)/proportionWidth)*proportionHeight);//约束比例
//限制最小矩形 宽
if (rightLine-leftLine<100){
leftLine=rightLine-100;
topLine=bottomLine-(((rightLine-leftLine)/proportionWidth)*proportionHeight);
//重绘
postInvalidate();
return true;
}
//限制最小矩形 高
if (bottomLine-topLine<100){
topLine=bottomLine-100;
leftLine=rightLine-((bottomLine-topLine)/proportionHeight)*proportionWidth;
//重绘
postInvalidate();
return true;
}
//防止超出边界
if (leftLine<0){
leftLine=0;
topLine=bottomLine-(((rightLine-leftLine)/proportionWidth)*proportionHeight);
}
//防止超出边界
if (topLine<0){
topLine=0;
leftLine=rightLine-((bottomLine-topLine)/proportionHeight)*proportionWidth;
}
//重绘
postInvalidate();
return true;
}else if (focus.equals(RIGHT_BOTTOM)){
//移动边线
rightLine=touchX;
bottomLine=topLine+(((rightLine-leftLine)/proportionWidth)*proportionHeight);//约束比例
//限制最小矩形 宽
if (rightLine-leftLine<100){
rightLine=leftLine+100;
bottomLine=topLine+(((rightLine-leftLine)/proportionWidth)*proportionHeight);
//重绘
postInvalidate();
return true;
}
//限制最小矩形 高
if (bottomLine-topLine<100){
bottomLine=topLine+100;
rightLine=leftLine+(((bottomLine-topLine)/proportionHeight)*proportionWidth);
//重绘
postInvalidate();
return true;
}
//防止超出边界
if (rightLine>widthSize){
rightLine=widthSize;
bottomLine=topLine+(((rightLine-leftLine)/proportionWidth)*proportionHeight);
}
//防止超出边界
if (bottomLine>heightSize){
bottomLine=heightSize;
rightLine=leftLine+(((bottomLine-topLine)/proportionHeight)*proportionWidth);
}
//重绘
postInvalidate();
return true;
}else if (focus.equals(BODY)){
float moveX=touchX-downX;
float moveY=touchY-downY;
leftLine=downLeftLine+moveX;
rightLine=downRightLine+moveX;
topLine=downTopLine+moveY;
bottomLine=downBottomLine+moveY;
if (leftLine<0){
rightLine=(rightLine-leftLine);
leftLine=0;
if (topLine<0){
bottomLine=bottomLine-topLine;
topLine=0;
//重绘
postInvalidate();
return true;
}
if (bottomLine>heightSize){
topLine=heightSize-(bottomLine-topLine);
bottomLine=heightSize;
//重绘
postInvalidate();
return true;
}
//重绘
postInvalidate();
return true;
}
if (rightLine>widthSize){
leftLine=widthSize-(rightLine-leftLine);
rightLine=widthSize;
if (topLine<0){
bottomLine=bottomLine-topLine;
topLine=0;
//重绘
postInvalidate();
return true;
}
if (bottomLine>heightSize){
topLine=heightSize-(bottomLine-topLine);
bottomLine=heightSize;
//重绘
postInvalidate();
return true;
}
//重绘
postInvalidate();
return true;
}
if (topLine<0){
bottomLine=bottomLine-topLine;
topLine=0;
//重绘
postInvalidate();
return true;
}
if (bottomLine>heightSize){
topLine=heightSize-(bottomLine-topLine);
bottomLine=heightSize;
//重绘
postInvalidate();
return true;
}
//重绘
postInvalidate();
return true;
}
return true;
}
//按下
private float downX,downY,downLeftLine,downTopLine,downRightLine,downBottomLine;
private boolean actionDown(float touchX, float touchY) {
downX=touchX;
downY=touchY;
downLeftLine=leftLine;
downTopLine=topLine;
downRightLine=rightLine;
downBottomLine=bottomLine;
Log.d("fxHou","按下X="+touchX+" touchY="+touchY);
boolean condition1=touchX>leftLine-40 && touchX<leftLine+40;
boolean condition2=touchY>topLine-40 && touchY<topLine+40;
if (condition1 && condition2){
Log.d("fxHou","左上获得焦点");
focus=LEFT_TOP;//左上获得焦点
return true;
}
boolean condition3=touchX>rightLine-40 && touchX<rightLine+40;
boolean condition4=touchY>bottomLine-40 && touchY<bottomLine+40;
if (condition3 && condition4){
Log.d("fxHou","右下获得焦点");
focus=RIGHT_BOTTOM;//右下获得焦点
return true;
}
boolean condition5=touchX>leftLine && touchX<rightLine;
boolean condition6=touchY>topLine && touchY<bottomLine;
if (condition5 && condition6){
Log.d("fxHou","整体获得焦点");
focus=BODY;//整体获得焦点
return true;
}
return true;
}
/**
* 设置要裁剪的位图
* @param bitmap 要裁剪的位图
* @param proportionWidth 比例：宽 如裁图比例3:4，此处传3
* @param proportionHeight 比例：高 如裁图比例3:4，此处传4
*/
public void setBitmap(Bitmap bitmap,int proportionWidth,int proportionHeight){
this.bitmap=bitmap;
bitmapWidth=bitmap.getWidth();
bimapHeight=bitmap.getHeight();
this.proportionWidth=proportionWidth;
this.proportionHeight=proportionHeight;
initTag=true;
postInvalidate();
}
/**
* 获取裁剪后的位图
* @param context
* @param minPixelWidth 限制最小宽度（像素）
* @param minPixelHeight 限制最小高度（像素）
* @return 裁切后的位图
*/
public Bitmap getBitmap(Context context,int minPixelWidth,int minPixelHeight){
if (bitmap==null)return null;
int startX= (int) (leftLine/scaleStep);
int startY= (int) (topLine/scaleStep);
int cutWidth=(int) ((rightLine/scaleStep)-(leftLine/scaleStep));
int cutHeight=(int) (bottomLine/scaleStep-topLine/scaleStep);
Bitmap newBitmap=Bitmap.createBitmap(bitmap,startX,startY,cutWidth,cutHeight,null,false);
if (newBitmap.getWidth()<minPixelWidth || newBitmap.getHeight()<minPixelHeight){
Toast.makeText(context, "图片太模糊了", Toast.LENGTH_SHORT).show();
return null;
}
return newBitmap;
}
}
使用方法
<com.example.cavasdemo.BitmapClippingView
android:id="@+id/my_cavas"
android:layout_width="match_parent"
android:layout_height="match_parent" />
BitmapClippingView my_cavas=(BitmapClippingView)findViewById(R.id.my_cavas);
//把刚刚本地相册拿到的bitmap传进去，用户进行自定义裁剪
my_cavas.setBitmap(bitmap,3,4);
//获取裁剪后的结果
Bitmap resulBitmap=my_cavas.getBitmap(context,600,800);
最后：拿到裁剪后的resulBitmap，做你想做的事。
