（图片缩放）自动适配屏幕支持缩放旋转，自动居中的imageview

废话不多说，直接代码。该imageview 只能代码里new出来使用。不能xml布局配置。有空再修改成可以配置使用的。

 

 

import android.content.Context;

import android.graphics.Bitmap;

import android.graphics.BitmapFactory;

import android.graphics.Canvas;

import android.graphics.Matrix;

import android.graphics.PointF;

import android.util.FloatMath;

import android.view.MotionEvent;

import android.widget.ImageView;

 

public class TouchImageView extends ImageView {

 

float x_down = 0; 

    float y_down = 0; 

    PointF start = new PointF(); 

    PointF mid = new PointF(); 

    float oldDist = 1f; 

    float oldRotation = 0; 

    Matrix matrix = new Matrix(); 

    Matrix matrix1 = new Matrix(); 

    Matrix savedMatrix = new Matrix(); 

 

    private static final int NONE = 0; 

    private static final int DRAG = 1; 

    private static final int ZOOM = 2; 

    int mode = NONE; 

 

    boolean matrixCheck = false; 

 

    int widthScreen; 

    int heightScreen; 

    

    //变换类型

    private static final int TYPE_WIDTH = 1;//只变宽度

    private static final int TYPE_HIGHT = 2;//只变高度

    private static final int TYPE_ALL = 3;//宽高都变

    private static final int TYPE_NONE = 4;//无变换

 

    Bitmap gintama; 

    

    public TouchImageView(Context ctx, Bitmap bmp, int screenWPix, int screenHPix) { 

        super(ctx);

        gintama = bmp;

        widthScreen = screenWPix;

        heightScreen = screenHPix;

        matrix = new Matrix(); 

        initBitmap();

    } 

 

    @Override

public void setImageBitmap(Bitmap bm) {

// TODO Auto-generated method stub

    gintama = bm;

    initBitmap();

}

    

@Override

public void setImageResource(int resId) {

// TODO Auto-generated method stub

gintama = BitmapFactory.decodeResource(getResources(), resId);

initBitmap();

}

 

protected void onDraw(Canvas canvas) { 

if(gintama == null) return;

        canvas.save(); 

        canvas.drawBitmap(gintama, matrix, null); 

        canvas.restore(); 

    } 

 

private void initBitmap()

{

    if(gintama == null) return;

float srcWidth = gintama.getWidth();

float srcHight = gintama.getHeight();

matrix.reset();

//偏移屏幕宽度的10%像素

float offset = widthScreen * 0.1f;

float width = widthScreen - offset;

float hight = heightScreen - offset;

 

//初始化移动距离

float dx = (widthScreen - srcWidth)/2f;

float dy = (heightScreen - srcHight)/2f;

 

int type = TYPE_NONE;

float scale = 1f;

if(srcWidth > width)

{

scale = width / srcWidth;

type = TYPE_WIDTH;

if(srcHight > hight)

{

float temp = hight / srcHight;

type = TYPE_ALL;

if(scale > temp)

{

scale = temp;

}

}

}else{

if(srcHight > hight)

{

scale = heightScreen / srcHight;

type = TYPE_HIGHT;

}

}

 

if(scale != 1f){

//缩放

matrix.postScale(scale, scale);

}

//移动

switch(type)

{

case TYPE_ALL:

case TYPE_HIGHT:

case TYPE_WIDTH:

dx = (widthScreen - srcWidth * scale) / 2f;

dy = (heightScreen - srcHight * scale) / 2f;

break;

}

matrix.postTranslate(dx, dy);

invalidate();

}

private long begin,end;

    public boolean onTouchEvent(MotionEvent event) { 

    if(gintama == null) return super.onTouchEvent(event);

        switch (event.getAction() & MotionEvent.ACTION_MASK) { 

        case MotionEvent.ACTION_DOWN: 

            mode = DRAG; 

            begin = System.currentTimeMillis();

            x_down = event.getX(); 

            y_down = event.getY(); 

            savedMatrix.set(matrix); 

            break; 

        case MotionEvent.ACTION_POINTER_DOWN: 

            mode = ZOOM; 

            oldDist = spacing(event); 

            oldRotation = rotation(event); 

            savedMatrix.set(matrix); 

            midPoint(mid, event); 

            break; 

        case MotionEvent.ACTION_MOVE: 

            if (mode == ZOOM) { 

                matrix1.set(savedMatrix); 

                float rotation = rotation(event) - oldRotation; 

                float newDist = spacing(event); 

                float scale = newDist / oldDist; 

                matrix1.postScale(scale, scale, mid.x, mid.y);// 縮放 

                matrix1.postRotate(rotation, mid.x, mid.y);// 旋轉 

                matrixCheck = matrixCheck(); 

                if (matrixCheck == false) { 

                    matrix.set(matrix1); 

                    invalidate(); 

                } 

            } else if (mode == DRAG) { 

                matrix1.set(savedMatrix); 

                matrix1.postTranslate(event.getX() - x_down, event.getY() 

                        - y_down);// 平移 

                matrixCheck = matrixCheck(); 

                if (matrixCheck == false) { 

                    matrix.set(matrix1); 

                    invalidate(); 

                } 

            } 

            break; 

        case MotionEvent.ACTION_UP:

        end = System.currentTimeMillis();

        case MotionEvent.ACTION_POINTER_UP: 

            mode = NONE;

            break;

        } 

        //点击时间区分是否是关闭

        if((end - begin) < 150)

        {

        return super.onTouchEvent(event);

        }else{

        return true;

        }

    } 

 

    private boolean matrixCheck() { 

        float[] f = new float[9]; 

        matrix1.getValues(f); 

        // 图片4个顶点的坐标 

        float x1 = f[0] * 0 + f[1] * 0 + f[2]; 

        float y1 = f[3] * 0 + f[4] * 0 + f[5]; 

        float x2 = f[0] * gintama.getWidth() + f[1] * 0 + f[2]; 

        float y2 = f[3] * gintama.getWidth() + f[4] * 0 + f[5]; 

        float x3 = f[0] * 0 + f[1] * gintama.getHeight() + f[2]; 

        float y3 = f[3] * 0 + f[4] * gintama.getHeight() + f[5]; 

        float x4 = f[0] * gintama.getWidth() + f[1] * gintama.getHeight() + f[2]; 

        float y4 = f[3] * gintama.getWidth() + f[4] * gintama.getHeight() + f[5]; 

        // 图片现宽度 

        double width = Math.sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2)); 

        // 缩放比率判断 

        if (width < widthScreen / 3 || width > widthScreen * 3) { 

            return true; 

        } 

        // 出界判断 

        if ((x1 < widthScreen / 3 && x2 < widthScreen / 3 

                && x3 < widthScreen / 3 && x4 < widthScreen / 3) 

                || (x1 > widthScreen * 2 / 3 && x2 > widthScreen * 2 / 3 

                        && x3 > widthScreen * 2 / 3 && x4 > widthScreen * 2 / 3) 

                || (y1 < heightScreen / 3 && y2 < heightScreen / 3 

                        && y3 < heightScreen / 3 && y4 < heightScreen / 3) 

                || (y1 > heightScreen * 2 / 3 && y2 > heightScreen * 2 / 3 

                        && y3 > heightScreen * 2 / 3 && y4 > heightScreen * 2 / 3)) { 

            return true; 

        } 

        return false; 

    } 

 

    // 触碰两点间距离 

    private float spacing(MotionEvent event) { 

        float x = event.getX(0) - event.getX(1); 

        float y = event.getY(0) - event.getY(1); 

        return FloatMath.sqrt(x * x + y * y); 

    } 

     

    // 取手势中心点 

    private void midPoint(PointF point, MotionEvent event) { 

        float x = event.getX(0) + event.getX(1); 

        float y = event.getY(0) + event.getY(1); 

        point.set(x / 2, y / 2); 

    } 

 

    // 取旋转角度 

    private float rotation(MotionEvent event) { 

        double delta_x = (event.getX(0) - event.getX(1)); 

        double delta_y = (event.getY(0) - event.getY(1)); 

        double radians = Math.atan2(delta_y, delta_x); 

        return (float) Math.toDegrees(radians); 

    } 

 

}