安卓Bitmap实现手势缩放、旋转、拖动

妖狐艹你老母 2022-09-02 12:00 335阅读 0赞

## 1、创建一个类MyImageView ##

import android.content.Context;
    import android.graphics.Matrix;
    import android.graphics.RectF;
    import android.graphics.drawable.Drawable;
    import android.util.AttributeSet;
    import android.view.MotionEvent;
    import android.view.ScaleGestureDetector;
    import android.view.View;
    import android.view.ViewTreeObserver;
    import androidx.appcompat.widget.AppCompatImageView;
    
    
    public class MyImageView extends AppCompatImageView implements ScaleGestureDetector.OnScaleGestureListener, View.OnTouchListener { 
        /** * 控件宽度 */
        private int mWidth;
        /** * 控件高度 */
        private int mHeight;
        /** * 拿到src的图片 */
        private Drawable mDrawable;
        /** * 图片宽度（使用前判断mDrawable是否null） */
        private int mDrawableWidth;
        /** * 图片高度（使用前判断mDrawable是否null） */
        private int mDrawableHeight;
    
        /** * 初始化缩放值 */
        private float mScale;
    
        /** * 双击图片的缩放值 */
        private float mDoubleClickScale;
    
        /** * 最大的缩放值 */
        private float mMaxScale;
    
        /** * 最小的缩放值 */
        private float mMinScale;
    
        private ScaleGestureDetector scaleGestureDetector;
        /** * 当前有着缩放值、平移值的矩阵。 */
        private Matrix matrix;
    
        public MyImageView(Context context) { 
            this(context, null);
        }
    
        public MyImageView(Context context, AttributeSet attrs) { 
            this(context, attrs, 0);
        }
    
        public MyImageView(Context context, AttributeSet attrs, int defStyleAttr) { 
            super(context, attrs, defStyleAttr);
            setOnTouchListener(this);
            scaleGestureDetector = new ScaleGestureDetector(context, this);
            initListener();
        }
    
    
        /** * 初始化事件监听 */
        private void initListener() { 
            // 强制设置模式
            setScaleType(ScaleType.MATRIX);
            // 添加观察者
            getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() { 
                @Override
                public void onGlobalLayout() { 
                    // 移除观察者
                    getViewTreeObserver().removeGlobalOnLayoutListener(this);
                    // 获取控件大小
                    mWidth = getWidth();
                    mHeight = getHeight();
    
                    //通过getDrawable获得Src的图片
                    mDrawable = getDrawable();
                    if (mDrawable == null)
                        return;
                    mDrawableWidth = mDrawable.getIntrinsicWidth();
                    mDrawableHeight = mDrawable.getIntrinsicHeight();
                    initImageViewSize();
                    moveToCenter();
                }
            });
        }
    
        /** * 初始化资源图片宽高 */
        private void initImageViewSize() { 
            if (mDrawable == null)
                return;
    
            // 缩放值
            float scale = 1.0f;
            // 图片宽度大于控件宽度，图片高度小于控件高度
            if (mDrawableWidth > mWidth && mDrawableHeight < mHeight)
                scale = mWidth * 1.0f / mDrawableWidth;
                // 图片高度度大于控件宽高，图片宽度小于控件宽度
            else if (mDrawableHeight > mHeight && mDrawableWidth < mWidth)
                scale = mHeight * 1.0f / mDrawableHeight;
                // 图片宽度大于控件宽度，图片高度大于控件高度
            else if (mDrawableHeight > mHeight && mDrawableWidth > mWidth)
                scale = Math.min(mHeight * 1.0f / mDrawableHeight, mWidth * 1.0f / mDrawableWidth);
                // 图片宽度小于控件宽度，图片高度小于控件高度
            else if (mDrawableHeight < mHeight && mDrawableWidth < mWidth)
                scale = Math.min(mHeight * 1.0f / mDrawableHeight, mWidth * 1.0f / mDrawableWidth);
            mScale = scale;
            mMaxScale = mScale * 8.0f;
            mMinScale = mScale * 0.5f;
        }
    
        /** * 移动控件中间位置 */
        private void moveToCenter() { 
            final float dx = mWidth / 2 - mDrawableWidth / 2;
            final float dy = mHeight / 2 - mDrawableHeight / 2;
            matrix = new Matrix();
            // 平移至中心
            matrix.postTranslate(dx, dy);
            // 以控件中心作为缩放
            matrix.postScale(mScale, mScale, mWidth / 2, mHeight / 2);
            setImageMatrix(matrix);
        }
    
        /** * @return 当前缩放的值 */
        private float getmScale() { 
            float[] floats = new float[9];
            matrix.getValues(floats);
            return floats[Matrix.MSCALE_X];
        }
    
        /** * @param matrix 矩阵 * @return matrix的 l t b r 和width，height */
        private RectF getRectf(Matrix matrix) { 
            RectF f = new RectF();
            if (mDrawable == null)
                return null;
            f.set(0, 0, mDrawableWidth, mDrawableHeight);
            matrix.mapRect(f);
            return f;
        }
    
        @Override
        public boolean onScale(ScaleGestureDetector detector) { 
            if (mDrawable == null) { 
                return true;
            }
            // 系统定义的缩放值
            float scaleFactor = detector.getScaleFactor();
            // 获取已经缩放的值
            float scale = getmScale();
            float scaleResult = scale * scaleFactor;
            if (scaleResult >= mMaxScale && scaleFactor > 1.0f)
                scaleFactor = mMaxScale / scale;
            if (scaleResult <= mMinScale && scaleFactor < 1.0f)
                scaleFactor = mMinScale / scale;
    
            matrix.postScale(scaleFactor, scaleFactor, detector.getFocusX(), detector.getFocusY());
    
            RectF f = getRectf(matrix);
            float dX = 0.0f;
            float dY = 0.0f;
            // 图片高度大于控件高度
            if (f.height() >= mHeight) { 
                // 图片顶部出现空白
                if (f.top > 0) { 
                    // 往上移动
                    dY = -f.top;
                }
                // 图片底部出现空白
                if (f.bottom < mHeight) { 
                    // 往下移动
                    dY = mHeight - f.bottom;
                }
            }
            // 图片宽度大于控件宽度
            if (f.width() >= mWidth) { 
                // 图片左边出现空白
                if (f.left > 0) { 
                    // 往左边移动
                    dX = -f.left;
                }
                // 图片右边出现空白
                if (f.right < mWidth) { 
                    // 往右边移动
                    dX = mWidth - f.right;
                }
            }
    
            if (f.width() < mWidth) { 
                dX = mWidth / 2 - f.right + f.width() / 2;
            }
    
            if (f.height() < mHeight) { 
                dY = mHeight / 2 - f.bottom + f.height() / 2;
            }
            matrix.postTranslate(dX, dY);
            setImageMatrix(matrix);
            return true;
        }
    
    
        @Override
        public boolean onScaleBegin(ScaleGestureDetector detector) { 
            return true;
        }
    
        @Override
        public void onScaleEnd(ScaleGestureDetector detector) { 
            float scale = getmScale();
            if (scale < mScale) { 
                matrix.postScale(mScale / scale, mScale / scale, mWidth / 2, mHeight / 2);
                setImageMatrix(matrix);
            }
        }
    
    
        private float downX;
        private float downY;
        private float nowMovingX;
        private float nowMovingY;
        private float lastMovedX;
        private float lastMovedY;
        private boolean isFirstMoved = false;
    
        @Override
        public boolean onTouch(View v, MotionEvent event) { 
            switch (event.getAction() & MotionEvent.ACTION_MASK) { 
                case MotionEvent.ACTION_DOWN:
                    isFirstMoved = false;
                    downX = event.getX();
                    downY = event.getY();
                    break;
                case MotionEvent.ACTION_POINTER_DOWN:
                    isFirstMoved = false;
                    break;
                case MotionEvent.ACTION_MOVE:
                    nowMovingX = event.getX();
                    nowMovingY = event.getY();
                    if (!isFirstMoved) { 
                        isFirstMoved = true;
                        lastMovedX = nowMovingX;
                        lastMovedY = nowMovingY;
                    }
                    float dX = 0.0f;
                    float dY = 0.0f;
                    RectF rectf = getRectf(matrix);
                    // 判断滑动方向
                    final float scrollX = nowMovingX - lastMovedX;
                    // 判断滑动方向
                    final float scrollY = nowMovingY - lastMovedY;
                    // 图片高度大于控件高度
                    if (rectf.height() > mHeight && canSmoothY()) { 
                        dY = nowMovingY - lastMovedY;
                    }
    
                    // 图片宽度大于控件宽度
                    if (rectf.width() > mWidth && canSmoothX()) { 
                        dX = nowMovingX - lastMovedX;
                    }
                    matrix.postTranslate(dX, dY);
    
                    remedyXAndY(dX,dY);
    
                    lastMovedX = nowMovingX;
                    lastMovedY = nowMovingY;
                    break;
                case MotionEvent.ACTION_UP:
                    break;
                case MotionEvent.ACTION_POINTER_UP:
                    isFirstMoved = false;
                    break;
            }
            return scaleGestureDetector.onTouchEvent(event);
        }
    
        /** * 判断x方向上能不能滑动 * @return 可以滑动返回true */
        private boolean canSmoothX(){ 
            RectF rectf = getRectf(matrix);
            if (rectf.left >0 || rectf.right <getWidth())
                return false;
            return true;
        }
    
        /** * 判断y方向上可不可以滑动 * @return 可以滑动返回true */
        private boolean canSmoothY(){ 
            RectF rectf = getRectf(matrix);
            if (rectf.top>0 || rectf.bottom < getHeight())
                return false;
            return true;
        }
    
        /** * 纠正出界的横和众线 * @param dx 出界偏移的横线 * @param dy 出街便宜的众线 */
        private void remedyXAndY(float dx,float dy){ 
            if (!canSmoothX())
                matrix.postTranslate(-dx,0);
            if (!canSmoothY())
                matrix.postTranslate(0,-dy);
            setImageMatrix(matrix);
        }
    }

## 2、引用这个类 ##

<?xml version="1.0" encoding="utf-8"?>
    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent">
    
        <com.example.testsize.MyImageView android:layout_width="match_parent" android:layout_height="match_parent" android:scaleType="matrix" android:src="@drawable/bg_monitor"/>
    
    </RelativeLayout>