android怎么实现简单的矩形裁剪框

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正常模式是这样的

简单的添加了等比例裁剪

贴代码

public class CutView extends View {    float downX;    float downY;    boolean isLeft;    boolean isRight;    boolean isTop;    boolean isBottom;    boolean isMove;    boolean isSlideLeft;    boolean isSlideRight;    boolean isSlideTop;    boolean isSlideBottom;     float rectLeft;    float rectRight;    float rectTop;    float rectBottom;    private int measuredWidth;    private int measuredHeight;    private Paint paint;    private int dp3;    private int cornerLength;    private int dp1;    private float aspect = -1;     public CutView(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        init();    }    public CutView(Context context, AttributeSet attrs) {        super(context, attrs);        init();    }    public CutView(Context context) {        super(context);        init();    }     private void init() {         dp3 = (int) getResources().getDimension(R.dimen.dp3);        dp1 = (int) getResources().getDimension(R.dimen.dp1);         paint = new Paint();        paint.setAntiAlias(true);        paint.setColor(Color.WHITE);        paint.setStyle(Paint.Style.STROKE);    }       @Override    public boolean onTouchEvent(MotionEvent event) {         switch (event.getAction()) {            case MotionEvent.ACTION_DOWN:                 downX = event.getX();                downY = event.getY();                 if(downX >= rectLeft && downX <= rectRight && downY >= rectTop && downY <= rectBottom){                    //判断手指的范围在左面还是右面                    int w = (int) ((rectRight - rectLeft)/3);                    if (downX >= rectLeft && downX <= rectLeft+w) {                        isLeft = true;                    } else if (downX <= rectRight && downX >= rectRight - w) {                        isRight = true;                    }                    //判断手指的范围在上面还是下面                    int h = (int) ((rectBottom - rectTop)/3);                    if (downY >= rectTop && downY <= rectTop+h) {                        isTop = true;                    } else if (downY <= rectBottom && downY >= rectBottom - h) {                        isBottom = true;                    }                    //如果手指范围没有在任何边界位置, 那么我们就认为用户是想拖拽框体                    if (!isLeft && !isTop && !isRight && !isBottom) {                        isMove = true;                    }                }                break;            case MotionEvent.ACTION_MOVE:                float moveX = event.getX();                float moveY = event.getY();                //得到手指移动距离                float slideX = moveX - downX ;                float slideY = moveY - downY;                 if (isMove) {//判断是否是拖拽模式                    rectLeft += slideX;                    rectRight += slideX;                    rectTop += slideY;                    rectBottom += slideY;                    //同时改变left和right值, 达到左右移动的效果                    if (rectLeft < 0 || rectRight > measuredWidth) {//判断x轴的移动边界                        rectLeft -= slideX;                        rectRight -= slideX;                    }                    //同时改变top和bottom值, 达到上下移动的效果                    if (rectTop < 0 || rectBottom > measuredHeight ) {//判断y轴的移动边界                        rectTop -= slideY;                        rectBottom -= slideY;                    }                    //实时触发onDraw()方法                    invalidate();                    downX = moveX;                    downY = moveY;                } else {                    if(aspect != -1){                        if(isLeft && (isTop || isBottom)){                            if(!isSlideLeft && !isSlideTop && !isSlideBottom){                                float x = Math.abs(slideX);                                float y = Math.abs(slideY);                                if(x > y && x > 10){                                    isSlideLeft = true;                                }else if(x < y && y >10){                                    if(isTop){                                        isSlideTop = true;                                    }else{                                        isSlideBottom = true;                                    }                                }                            }                        }else if (isRight && (isTop || isBottom)){                            if(!isSlideRight && !isSlideTop && !isSlideBottom){                                float x = Math.abs(slideX);                                float y = Math.abs(slideY);                                if(x > y && x > 10){                                    isSlideRight = true;                                }else if(x < y && y >10){                                    if(isTop){                                        isSlideTop = true;                                    }else{                                        isSlideBottom = true;                                    }                                }                            }                        }else if(isLeft && !isSlideLeft){                            isSlideLeft = true;                        }else if(isRight && !isSlideLeft){                            isSlideRight = true;                        }else if(isTop && !isSlideTop){                            isSlideTop = true;                        }else if(isBottom && !isSlideBottom){                            isSlideBottom = true;                        }                        if (isSlideLeft) {                            rectLeft += slideX;                            if (rectLeft < 0) rectLeft = 0;                            float w = rectRight - rectLeft;                            if(w < cornerLength * 2){                                w = cornerLength * 2;                                rectLeft = rectRight - w;                            }                            float h = w/aspect;                            if(h < cornerLength * 2){                                h = cornerLength * 2;                                w = h *aspect;                                rectLeft = rectRight - w;                            }                            if(isTop){                                rectBottom = rectTop + h;                            }else if(isBottom){                                rectTop = rectBottom - h;                            }else{                                float rh = rectBottom - rectTop;                                float t = (rh - h)/2;                                rectTop += t;                                rectBottom -= t;                            }                            if(rectTop < 0){                                rectTop = 0;                                rectBottom = h;                                if(rectBottom > measuredHeight){                                    rectBottom =  measuredHeight;                                }                                w = rectBottom *aspect;                                rectLeft = rectRight - w;                            }else if(rectBottom > measuredHeight){                                rectBottom = measuredHeight;                                rectTop = measuredHeight - h;                                if(rectTop < 0){                                    rectTop = 0;                                }                                w = (rectBottom - rectTop) *aspect;                                rectLeft = rectRight - w;                            }                            invalidate();                            downX = moveX;                            downY = moveY;                        } else if (isSlideRight) {                            rectRight += slideX;                            if (rectRight > measuredWidth )                                rectRight = measuredWidth;                            float w = rectRight - rectLeft;                            if(w < cornerLength * 2){                                w = cornerLength * 2;                                rectRight = rectLeft + w;                            }                            float h = w/aspect;                            if(h < cornerLength * 2){                                h = cornerLength * 2;                                w = h *aspect;                                rectRight = rectLeft + w;                            }                             if(isTop){                                rectBottom = rectTop + h;                            }else if(isBottom){                                rectTop = rectBottom - h;                            }else{                                float rh = rectBottom - rectTop;                                float t = (rh - h)/2;                                rectTop += t;                                rectBottom -= t;                            }                            if(rectTop < 0){                                rectTop = 0;                                rectBottom = h;                                if(rectBottom > measuredHeight){                                    rectBottom =  measuredHeight;                                }                                w = rectBottom *aspect;                                rectRight = rectLeft + w;                            }else if(rectBottom > measuredHeight){                                rectBottom = measuredHeight;                                rectTop = measuredHeight - h;                                if(rectTop < 0){                                    rectTop = 0;                                }                                w = (rectBottom - rectTop) *aspect;                                rectRight = rectLeft + w;                            }                            invalidate();                            downX = moveX;                            downY = moveY;                        }else if (isSlideTop) {                            rectTop += slideY;                            if (rectTop < 0) rectTop = 0;                            float h = rectBottom - rectTop;                            if(h < cornerLength * 2){                                h = cornerLength * 2;                                rectTop = rectBottom - h;                            }                            float w = h*aspect;                            if(w < cornerLength * 2){                                w = cornerLength * 2;                                h = w /aspect;                                rectTop = rectBottom - h;                            }                             if(isLeft){                                rectRight = rectLeft + w;                            }else if(isRight){                                rectLeft = rectRight - w;                            }else{                                float rw = rectRight - rectLeft;                                float t = (rw - w)/2;                                rectLeft += t;                                rectRight -= t;                            }                            if(rectLeft < 0){                                rectLeft = 0;                                rectRight = w;                                if(rectRight > measuredWidth){                                    rectRight = measuredWidth;                                }                                h = rectRight /aspect;                                rectTop = rectBottom - h;                            }else if(rectRight > measuredWidth){                                rectRight = measuredWidth;                                rectLeft = measuredWidth - w;                                if(rectLeft < 0){                                    rectLeft = 0;                                    w = measuredWidth;                                }                                h = w /aspect;                                rectTop = rectBottom - h;                            }                            invalidate();                            downX = moveX;                            downY = moveY;                        } else if (isSlideBottom) {                            rectBottom += slideY;                            if (rectBottom > measuredHeight )                                rectBottom = measuredHeight ;                            float h = rectBottom - rectTop;                            if(h < cornerLength * 2){                                h = cornerLength * 2;                                rectBottom = rectTop + h;                            }                            float w = h*aspect;                            if(w < cornerLength * 2){                                w = cornerLength * 2;                                h = w /aspect;                                rectBottom = rectTop + h;                            }                             if(isLeft){                                rectRight = rectLeft + w;                            }else if(isRight){                                rectLeft = rectRight - w;                            }else{                                float rw = rectRight - rectLeft;                                float t = (rw - w)/2;                                rectLeft += t;                                rectRight -= t;                            }                            if(rectLeft < 0){                                rectLeft = 0;                                rectRight = w;                                if(rectRight > measuredWidth){                                    rectRight = measuredWidth;                                }                                h = rectRight /aspect;                                rectBottom = rectTop + h;                            }else if(rectRight > measuredWidth){                                rectRight = measuredWidth;                                rectLeft = measuredWidth - w;                                if(rectLeft < 0){                                    rectLeft = 0;                                    w = measuredWidth;                                }                                h = w /aspect;                                rectBottom = rectTop + h;                            }                            invalidate();                            downX = moveX;                            downY = moveY;                        }                    }else{                        if (isLeft) {                            rectLeft += slideX;                            if (rectLeft < 0) rectLeft = 0;                            if (rectLeft > rectRight - cornerLength * 2)                                rectLeft = rectRight - cornerLength * 2;                        } else if (isRight) {                            rectRight += slideX;                            if (rectRight > measuredWidth )                                rectRight = measuredWidth;                            if (rectRight < rectLeft + cornerLength * 2)                                rectRight = rectLeft + cornerLength * 2;                        }                        //改变边框的高度, 如果两个都满足(比如手指在边角位置),那么就呈现一种缩放状态                        if (isTop) {                            rectTop += slideY;                            if (rectTop < 0) rectTop = 0;                            if (rectTop > rectBottom - cornerLength * 2)                                rectTop = rectBottom - cornerLength * 2;                        } else if (isBottom) {                            rectBottom += slideY;                            if (rectBottom > measuredHeight )                                rectBottom = measuredHeight ;                            if (rectBottom < rectTop + cornerLength * 2)                                rectBottom = rectTop + cornerLength * 2;                        }                        invalidate();                        downX = moveX;                        downY = moveY;                    }                 }                break;            case MotionEvent.ACTION_CANCEL:            case MotionEvent.ACTION_UP:                isLeft = false;                isRight = false;                isTop = false;                isBottom = false;                isMove = false;                isSlideLeft = false;                isSlideRight = false;                isSlideTop = false;                isSlideBottom = false;                break;        }        return true;    }         public float[] getCutArr() {         float[] arr = new float[4];        arr[0] = rectLeft ;        arr[1] = rectTop ;        arr[2] = rectRight ;        arr[3] = rectBottom ;        return arr;    }     public int getRectWidth() {        return (int) (measuredWidth);    }     public int getRectHeight() {        return (int) (measuredHeight);    }      public void setAspect(float aspect){        this.aspect = aspect;    }    @Override    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {        super.onMeasure(widthMeasureSpec, heightMeasureSpec);         if (measuredWidth == 0) {            initParams();        }    }     private void initParams() {         measuredWidth = getMeasuredWidth();        measuredHeight = getMeasuredHeight();         if(aspect == -1){            cornerLength = measuredWidth / 6;            rectRight = measuredWidth ;            rectLeft = 0;            rectTop = 0;            rectBottom = measuredHeight ;        }else{            float vh = measuredWidth*1.0f/measuredHeight;            if(aspect > 1){                cornerLength = measuredWidth / 6;            }else{                cornerLength = measuredHeight / 6;            }            if(aspect > vh){                rectLeft = 0;                rectRight = measuredWidth;                float h = measuredWidth/aspect;                rectTop = (measuredHeight - h)/2;                rectBottom = rectTop + h;            }else{                rectTop = 0;                rectBottom = measuredHeight;                float w = measuredHeight*aspect;                rectLeft = (measuredWidth - w)/2;                rectRight = rectLeft + w;            }        }    }     @Override    protected void onDraw(canvas canvas) {         paint.setStrokeWidth(dp1);        //绘制裁剪区域的矩形, 传入margin值来确定大小        canvas.drawRect(rectLeft, rectTop, rectRight, rectBottom, paint);        //绘制四条分割线和四个角        drawLine(canvas, rectLeft, rectTop, rectRight, rectBottom);    }         private void drawLine(Canvas canvas, float left, float top, float right, float bottom) {         paint.setStrokeWidth(1);        //绘制四条分割线        float startX = (right - left) / 3 + left;        float startY = top;        float stopX = (right - left) / 3 + left;        float stopY = bottom;        canvas.drawLine(startX, startY, stopX, stopY, paint);         startX = (right - left) / 3 * 2 + left;        startY = top;        stopX = (right - left) / 3 * 2 + left;        stopY = bottom;        canvas.drawLine(startX, startY, stopX, stopY, paint);         startX = left;        startY = (bottom - top) / 3 + top;        stopX = right;        stopY = (bottom - top) / 3 + top;        canvas.drawLine(startX, startY, stopX, stopY, paint);         startX = left;        startY = (bottom - top) / 3 * 2 + top;        stopX = right;        stopY = (bottom - top) / 3 * 2 + top;        canvas.drawLine(startX, startY, stopX, stopY, paint);         paint.setStrokeWidth(dp3);        //绘制四个角        startX = left - dp3 / 2;        startY = top;        stopX = left + cornerLength;        stopY = top;        canvas.drawLine(startX, startY, stopX, stopY, paint);        startX = left;        startY = top;        stopX = left;        stopY = top + cornerLength;        canvas.drawLine(startX, startY, stopX, stopY, paint);         startX = right + dp3 / 2;        startY = top;        stopX = right - cornerLength;        stopY = top;        canvas.drawLine(startX, startY, stopX, stopY, paint);        startX = right;        startY = top;        stopX = right;        stopY = top + cornerLength;        canvas.drawLine(startX, startY, stopX, stopY, paint);         startX = left;        startY = bottom;        stopX = left;        stopY = bottom - cornerLength;        canvas.drawLine(startX, startY, stopX, stopY, paint);        startX = left - dp3 / 2;        startY = bottom;        stopX = left + cornerLength;        stopY = bottom;        canvas.drawLine(startX, startY, stopX, stopY, paint);         startX = right + dp3 / 2;        startY = bottom;        stopX = right - cornerLength;        stopY = bottom;        canvas.drawLine(startX, startY, stopX, stopY, paint);        startX = right;        startY = bottom;        stopX = right;        stopY = bottom - cornerLength;        canvas.drawLine(startX, startY, stopX, stopY, paint);    }}

使用的时候，只要把这个CutView盖在图片的View上，CutView的宽高必须和图片View的显示宽高一样

我是这样计算的

int screenWidth = mWidthPixels;int screenHeight = mHeightPixels; int left,top,viewWidth,viewHeight;float sh = screenWidth*1.0f/screenHeight;float vh = videoWidth *1.0f/ videoHeight;if(sh < vh){    left = 0;    viewWidth = screenWidth;    viewHeight = (int)(videoHeight *1.0f/ videoWidth *viewWidth);    top = (screenHeight - viewHeight)/2;}else{    top = 0;    viewHeight = screenHeight;    viewWidth = (int)(videoWidth *1.0f/ videoHeight *viewHeight);    left = (screenWidth - viewWidth)/2;}LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(viewWidth,viewHeight);params.leftMargin = left;params.topMargin = top;params.bottomMargin = mHeightPixels - top - viewHeight;videoView.setLayoutParams(params);

设置是否比例画框

cutView.setAspect(-1);

-1表示不用，需要比例显示的话就传入width*1.0f/heigh

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