/**
* 自定義的ImageView控制，可對(duì)圖片進(jìn)行多點(diǎn)觸控縮放和拖動(dòng)
* 
* @author qiuwanyong
*/
public class MyImageView extends ImageView {
/**
* 初始化狀態(tài)常量
*/
public static final int STATUS_INIT = 1;
/**
* 圖片放大狀態(tài)常量
*/
public static final int STATUS_ZOOM_OUT = 2;
/**
* 圖片縮小狀態(tài)常量
*/
public static final int STATUS_ZOOM_IN = 3;
/**
* 圖片拖動(dòng)狀態(tài)常量
*/
public static final int STATUS_MOVE = 4;
/**
* 用于對(duì)圖片進(jìn)行移動(dòng)和縮放變換的矩陣
*/
private Matrix matrix = new Matrix();
/**
* 待展示的Bitmap對(duì)象
*/
private Bitmap sourceBitmap;
/**
* 記錄當(dāng)前操作的狀態(tài)，可選值為STATUS_INIT、STATUS_ZOOM_OUT、STATUS_ZOOM_IN和STATUS_MOVE
*/
private int currentStatus;
/**
* ZoomImageView控件的寬度
*/
private int width;
/**
* ZoomImageView控件的高度
*/
private int height;
/**
* 記錄兩指同時(shí)放在屏幕上時(shí)，中心點(diǎn)的橫坐標(biāo)值
*/
private float centerPointX;
/**
* 記錄兩指同時(shí)放在屏幕上時(shí)，中心點(diǎn)的縱坐標(biāo)值
*/
private float centerPointY;
/**
* 記錄當(dāng)前圖片的寬度，圖片被縮放時(shí)，這個(gè)值會(huì)一起變動(dòng)
*/
private float currentBitmapWidth;
/**
* 記錄當(dāng)前圖片的高度，圖片被縮放時(shí)，這個(gè)值會(huì)一起變動(dòng)
*/
private float currentBitmapHeight;
/**
* 記錄上次手指移動(dòng)時(shí)的橫坐標(biāo)
*/
private float lastXMove = -1;
/**
* 記錄上次手指移動(dòng)時(shí)的縱坐標(biāo)
*/
private float lastYMove = -1;
/**
* 記錄手指在橫坐標(biāo)方向上的移動(dòng)距離
*/
private float movedDistanceX;
/**
* 記錄手指在縱坐標(biāo)方向上的移動(dòng)距離
*/
private float movedDistanceY;
/**
* 記錄圖片在矩陣上的橫向偏移值
*/
private float totalTranslateX;
/**
* 記錄圖片在矩陣上的縱向偏移值
*/
private float totalTranslateY;
/**
* 記錄圖片在矩陣上的總縮放比例
*/
private float totalRatio;
/**
* 記錄手指移動(dòng)的距離所造成的縮放比例
*/
private float scaledRatio;
/**
* 記錄圖片初始化時(shí)的縮放比例
*/
private float initRatio;
/**
* 記錄上次兩指之間的距離
*/
private double lastFingerDis;
/**
* ZoomImageView構(gòu)造函數(shù)，將當(dāng)前操作狀態(tài)設(shè)為STATUS_INIT。
* 
* @param context
* @param attrs
*/
public MyImageView(Context context, AttributeSet attrs) {
super(context, attrs);
currentStatus = STATUS_INIT;
}
/**
* 將待展示的圖片設(shè)置進(jìn)來(lái)。
* 
* @param bitmap
* 待展示的Bitmap對(duì)象
*/
public void setImageBitmap(Bitmap bitmap) {
sourceBitmap = bitmap;
invalidate();
}
@Override
protected void onLayout(boolean changed, int left, int top, int right,
int bottom) {
super.onLayout(changed, left, top, right, bottom);
if (changed) {
// 分別獲取到ZoomImageView的寬度和高度
width = getWidth();
height = getHeight();
}
}
@SuppressLint("NewApi") @Override
public boolean onTouchEvent(MotionEvent event) {
if (initRatio == totalRatio) {
getParent().requestDisallowInterceptTouchEvent(false);
} else {
getParent().requestDisallowInterceptTouchEvent(true);
}
switch (event.getActionMasked()) {
case MotionEvent.ACTION_POINTER_DOWN:
if (event.getPointerCount() == 2) {
// 當(dāng)有兩個(gè)手指按在屏幕上時(shí)，計(jì)算兩指之間的距離
lastFingerDis = distanceBetweenFingers(event);
}
break;
case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_MOVE:
if (event.getPointerCount() == 1) {
// 只有單指按在屏幕上移動(dòng)時(shí)，為拖動(dòng)狀態(tài)
float xMove = event.getX();
float yMove = event.getY();
if (lastXMove == -1 && lastYMove == -1) {
lastXMove = xMove;
lastYMove = yMove;
}
currentStatus = STATUS_MOVE;
movedDistanceX = xMove - lastXMove;
movedDistanceY = yMove - lastYMove;
// 進(jìn)行邊界檢查，不允許將圖片拖出邊界
if (totalTranslateX + movedDistanceX > 0) {
movedDistanceX = 0;
} else if (width - (totalTranslateX + movedDistanceX) > currentBitmapWidth) {
movedDistanceX = 0;
}
if (totalTranslateY + movedDistanceY > 0) {
movedDistanceY = 0;
} else if (height - (totalTranslateY + movedDistanceY) > currentBitmapHeight) {
movedDistanceY = 0;
}
// 調(diào)用onDraw()方法繪制圖片
invalidate();
lastXMove = xMove;
lastYMove = yMove;
} else if (event.getPointerCount() == 2) {
// 有兩個(gè)手指按在屏幕上移動(dòng)時(shí)，為縮放狀態(tài)
centerPointBetweenFingers(event);
double fingerDis = distanceBetweenFingers(event);
if (fingerDis > lastFingerDis) {
currentStatus = STATUS_ZOOM_OUT;
} else {
currentStatus = STATUS_ZOOM_IN;
}
// 進(jìn)行縮放倍數(shù)檢查，最大只允許將圖片放大4倍，最小可以縮小到初始化比例
if ((currentStatus == STATUS_ZOOM_OUT && totalRatio < 4 * initRatio)
|| (currentStatus == STATUS_ZOOM_IN && totalRatio > initRatio)) {
scaledRatio = (float) (fingerDis / lastFingerDis);
totalRatio = totalRatio * scaledRatio;
if (totalRatio > 4 * initRatio) {
totalRatio = 4 * initRatio;
} else if (totalRatio < initRatio) {
totalRatio = initRatio;
}
// 調(diào)用onDraw()方法繪制圖片
invalidate();
lastFingerDis = fingerDis;
}
}
break;
case MotionEvent.ACTION_POINTER_UP:
if (event.getPointerCount() == 2) {
// 手指離開(kāi)屏幕時(shí)將臨時(shí)值還原
lastXMove = -1;
lastYMove = -1;
}
break;
case MotionEvent.ACTION_UP:
// 手指離開(kāi)屏幕時(shí)將臨時(shí)值還原
lastXMove = -1;
lastYMove = -1;
break;
default:
break;
}
return true;
}
/**
* 根據(jù)currentStatus的值來(lái)決定對(duì)圖片進(jìn)行什么樣的繪制操作。
*/
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
switch (currentStatus) {
case STATUS_ZOOM_OUT:
case STATUS_ZOOM_IN:
zoom(canvas);
break;
case STATUS_MOVE:
move(canvas);
break;
case STATUS_INIT:
initBitmap(canvas);
default:
if (sourceBitmap != null) {
canvas.drawBitmap(sourceBitmap, matrix, null);
}
break;
}
}
/**
* 對(duì)圖片進(jìn)行縮放處理。
* 
* @param canvas
*/
private void zoom(Canvas canvas) {
matrix.reset();
// 將圖片按總縮放比例進(jìn)行縮放
matrix.postScale(totalRatio, totalRatio);
float scaledWidth = sourceBitmap.getWidth() * totalRatio;
float scaledHeight = sourceBitmap.getHeight() * totalRatio;
float translateX = 0f;
float translateY = 0f;
// 如果當(dāng)前圖片寬度小于屏幕寬度，則按屏幕中心的橫坐標(biāo)進(jìn)行水平縮放。否則按兩指的中心點(diǎn)的橫坐標(biāo)進(jìn)行水平縮放
if (currentBitmapWidth < width) {
translateX = (width - scaledWidth) / 2f;
} else {
translateX = totalTranslateX * scaledRatio + centerPointX
* (1 - scaledRatio);
// 進(jìn)行邊界檢查，保證圖片縮放后在水平方向上不會(huì)偏移出屏幕
if (translateX > 0) {
translateX = 0;
} else if (width - translateX > scaledWidth) {
translateX = width - scaledWidth;
}
}
// 如果當(dāng)前圖片高度小于屏幕高度，則按屏幕中心的縱坐標(biāo)進(jìn)行垂直縮放。否則按兩指的中心點(diǎn)的縱坐標(biāo)進(jìn)行垂直縮放
if (currentBitmapHeight < height) {
translateY = (height - scaledHeight) / 2f;
} else {
translateY = totalTranslateY * scaledRatio + centerPointY
* (1 - scaledRatio);
// 進(jìn)行邊界檢查，保證圖片縮放后在垂直方向上不會(huì)偏移出屏幕
if (translateY > 0) {
translateY = 0;
} else if (height - translateY > scaledHeight) {
translateY = height - scaledHeight;
}
}
// 縮放后對(duì)圖片進(jìn)行偏移，以保證縮放后中心點(diǎn)位置不變
matrix.postTranslate(translateX, translateY);
totalTranslateX = translateX;
totalTranslateY = translateY;
currentBitmapWidth = scaledWidth;
currentBitmapHeight = scaledHeight;
canvas.drawBitmap(sourceBitmap, matrix, null);
}
/**
* 對(duì)圖片進(jìn)行平移處理
* 
* @param canvas
*/
private void move(Canvas canvas) {
matrix.reset();
// 根據(jù)手指移動(dòng)的距離計(jì)算出總偏移值
float translateX = totalTranslateX + movedDistanceX;
float translateY = totalTranslateY + movedDistanceY;
// 先按照已有的縮放比例對(duì)圖片進(jìn)行縮放
matrix.postScale(totalRatio, totalRatio);
// 再根據(jù)移動(dòng)距離進(jìn)行偏移
matrix.postTranslate(translateX, translateY);
totalTranslateX = translateX;
totalTranslateY = translateY;
canvas.drawBitmap(sourceBitmap, matrix, null);
}
/**
* 對(duì)圖片進(jìn)行初始化操作，包括讓圖片居中，以及當(dāng)圖片大于屏幕寬高時(shí)對(duì)圖片進(jìn)行壓縮。
* 
* @param canvas
*/
private void initBitmap(Canvas canvas) {
if (sourceBitmap != null) {
matrix.reset();
int bitmapWidth = sourceBitmap.getWidth();
int bitmapHeight = sourceBitmap.getHeight();
if (bitmapWidth > width || bitmapHeight > height) {
if (bitmapWidth - width > bitmapHeight - height) {
// 當(dāng)圖片寬度大于屏幕寬度時(shí)，將圖片等比例壓縮，使它可以完全顯示出來(lái)
float ratio = width / (bitmapWidth * 1.0f);
matrix.postScale(ratio, ratio);
float translateY = (height - (bitmapHeight * ratio)) / 2f;
// 在縱坐標(biāo)方向上進(jìn)行偏移，以保證圖片居中顯示
matrix.postTranslate(0, translateY);
totalTranslateY = translateY;
totalRatio = initRatio = ratio;
} else {
// 當(dāng)圖片高度大于屏幕高度時(shí)，將圖片等比例壓縮，使它可以完全顯示出來(lái)
float ratio = height / (bitmapHeight * 1.0f);
matrix.postScale(ratio, ratio);
float translateX = (width - (bitmapWidth * ratio)) / 2f;
// 在橫坐標(biāo)方向上進(jìn)行偏移，以保證圖片居中顯示
matrix.postTranslate(translateX, 0);
totalTranslateX = translateX;
totalRatio = initRatio = ratio;
}
currentBitmapWidth = bitmapWidth * initRatio;
currentBitmapHeight = bitmapHeight * initRatio;
} else {
// 當(dāng)圖片的寬高都小于屏幕寬高時(shí)，直接讓圖片居中顯示
float translateX = (width - sourceBitmap.getWidth()) / 2f;
float translateY = (height - sourceBitmap.getHeight()) / 2f;
matrix.postTranslate(translateX, translateY);
totalTranslateX = translateX;
totalTranslateY = translateY;
totalRatio = initRatio = 1f;
currentBitmapWidth = bitmapWidth;
currentBitmapHeight = bitmapHeight;
}
canvas.drawBitmap(sourceBitmap, matrix, null);
}
}
/**
* 計(jì)算兩個(gè)手指之間的距離。
* 
* @param event
* @return 兩個(gè)手指之間的距離
*/
@SuppressLint("NewApi") private double distanceBetweenFingers(MotionEvent event) {
float disX = Math.abs(event.getX(0) - event.getX(1));
float disY = Math.abs(event.getY(0) - event.getY(1));
return Math.sqrt(disX * disX + disY * disY);
}
/**
* 計(jì)算兩個(gè)手指之間中心點(diǎn)的坐標(biāo)。
* 
* @param event
*/
@SuppressLint("NewApi") private void centerPointBetweenFingers(MotionEvent event) {
float xPoint0 = event.getX(0);
float yPoint0 = event.getY(0);
float xPoint1 = event.getX(1);
float yPoint1 = event.getY(1);
centerPointX = (xPoint0 + xPoint1) / 2;
centerPointY = (yPoint0 + yPoint1) / 2;
}
}