自己定义ImageView，实现点击之后算出点击的是身体的哪个部位
近期也是由于项目的原因，所以有机会接触到这边的算法。 此文重点不是怎样实现的思路和原理， 有须要的同事能够借鉴一下
废话不多说，直接上代码：
<span style="font-size:18px;"><span style="font-size:18px;">public class MyImage extends ImageView {
private DisplayMetrics dm;
private int bodyImageViewHeight = 0;
private int bodyImageViewWidth = 0;
public MyImage(Context context) {
super(context);
}
public MyImage(Context context, AttributeSet attrs) {
super(context, attrs);
dm = context.getResources().getDisplayMetrics();
}
@Override
public boolean onTouchEvent(MotionEvent event) {
int x = (int) event.getX();
int y = (int) event.getY();
//初始化各个部位的范围
initParametersForRegion();
if(isTouchPointInTransparent(x, y)) {
Log.e("mcoy", "the point is in transparent area now");
} else {
positionType position = pointToPosition(x, y);
Log.e("mcoy", "the position is " + position);
}
return super.onTouchEvent(event);
}
private enum positionType{
REGION_FRONT_HAND,
REGION_FRONT_HEAD,
REGION_FRONT_CHEST,
REGION_FRONT_WAIST,
REGION_FRONT_LEG
}
private positionType pointToPosition(int x, int y) {
if(x < mHandX1 || x > mHandX2)
return positionType.REGION_FRONT_HAND;
else if (y < mHeadY)
return positionType.REGION_FRONT_HEAD;
else if(y < mChestY)
return positionType.REGION_FRONT_CHEST;
else if(y < mWaistY)
return positionType.REGION_FRONT_WAIST;
else
return positionType.REGION_FRONT_LEG;
}
/**
*
* @param x
* @param y
* @return 推断点击区域是否在透明区域
*/
private boolean isTouchPointInTransparent(int x, int y) {
int paddingLeft = this.getPaddingLeft();
int paddingTop = this.getPaddingTop();
int imageHeight = this.getHeight();
int imageWidth = this.getWidth();
Drawable drawable = this.getDrawable();
Bitmap bitmap = ((BitmapDrawable) drawable).getBitmap();
int intrinsicHeight = drawable.getIntrinsicHeight();
int intrinsicWidth = drawable.getIntrinsicWidth();
int locationInBitmapX = (x - paddingLeft) * intrinsicWidth / imageWidth;
int locationInBitmapY = (y - paddingTop) * intrinsicHeight / imageHeight;
int pixel = bitmap.getPixel(locationInBitmapX, locationInBitmapY);
Log.e("mcoy", "x is " + x);
Log.e("mcoy", "y is " + y);
Log.e("mcoy", "imageHeight is " + imageHeight);
Log.e("mcoy", "imageWidth is " + imageWidth);
Log.e("mcoy", "intrinsicHeight is " + intrinsicHeight);
Log.e("mcoy", "intrinsicWidth is " + intrinsicWidth);
Log.e("mcoy", "locationInBitmapX is " + locationInBitmapX);
Log.e("mcoy", "locationInBitmapY is " + locationInBitmapY);
Log.e("mcoy", "actualBitmapX is " + locationInBitmapX / dm.density);
Log.e("mcoy", "actualBitmapY is " + locationInBitmapY / dm.density);
Log.e("mcoy", "pixel is " + pixel);
return pixel == 0;
}
private int mHeadY;
private int mHandX1;
private int mHandX2;
private int mChestY;
private int mWaistY;
//下面数据须要同UI同事沟通好每一个部位定义的范围。或者自己手动量一下
private final int HEAD_AREA = 130;
private final int LEFT_HAND_AREA = 126;
private final int RIGHT_HAND_AREA = 280;
private final int CHEST_AREA = 260;
private final int WAIST_AREA = 417;
private void initParametersForRegion() {
if(bodyImageViewHeight != this.getHeight()) {
bodyImageViewHeight = this.getHeight();
bodyImageViewWidth = this.getWidth();
int imageIntrinsicHeight = this.getDrawable().getIntrinsicHeight();
int imageIntrinsicWidht = this.getDrawable().getIntrinsicWidth();
Log.e("danny", "bodyImageViewHeight is " + bodyImageViewHeight);
Log.e("danny", "bodyImageViewWidth is " + bodyImageViewWidth);
Log.e("danny", "imageIntrinsicHeight is " + imageIntrinsicHeight);
Log.e("danny", "imageIntrinsicWidht is " + imageIntrinsicWidht);
mHeadY = DensityUtil.dip2px(getContext(), HEAD_AREA) * bodyImageViewHeight / imageIntrinsicHeight
+ this.getPaddingTop();
mHandX1 = DensityUtil.dip2px(getContext(), LEFT_HAND_AREA) * bodyImageViewWidth / imageIntrinsicWidht
+ this.getPaddingLeft();
mHandX2 = DensityUtil.dip2px(getContext(), RIGHT_HAND_AREA) * bodyImageViewWidth / imageIntrinsicWidht
+ this.getPaddingLeft();
mChestY = DensityUtil.dip2px(getContext(), CHEST_AREA) * bodyImageViewHeight / imageIntrinsicHeight
+ this.getPaddingTop();
mWaistY = DensityUtil.dip2px(getContext(), WAIST_AREA) * bodyImageViewHeight / imageIntrinsicHeight
+ this.getPaddingTop();
Log.e("danny", "mHeadY is " + mHeadY);
Log.e("danny", "mHandX1 is " + mHandX1);
Log.e("danny", "mHandX2 is " + mHandX2);
Log.e("danny", "mChestY is " + mChestY);
Log.e("danny", "mWaistY is " + mWaistY);
}
}
}</span></span>代码非常easy， 就是一个自己实现的ImageView， 可是有几点须要注意的点：
1 图片须要跟UI同事沟通好对应坐标(认真看完代码之后就会知道原因), 假设换图片的话。那HEAD_AREA等值可能须要又一次定义
2 算法思路---在不同的desity的的设备上。 我们都能够算出图片相应的drawable的width/height，而图片缩放或者是放大是依照比例缩放/放大， 因此我们能够得出例如以下等式：
touchX / imageWidth = positonInBitmap / drawable.getIntransicWidth ;
==> positonInBitmap = touchX * drawable.getIntransicWidth / imageWidth;
touchX是点击在ImageView上的x坐标；imageWidth是图片的宽度。positionInBitmap是touchX映射在ImageView所相应drawable上的x坐标(这句话有点拗口，能够细致想一下)
下面是xml文件：
<span style="font-size:18px;"><span style="font-size:18px;"><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.mcoy.pixelinbitmaptest.MainActivity" >
<TextView
android:id="@+id/tv"
android:layout_width="wrap_content"
android:layout_height="80dp"
android:text="@string/hello_world" />
<com.example.jiangxinxing.views.MyImage
android:id="@+id/iv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:adjustViewBounds="true"
android:scaleType="fitXY"
android:src="@drawable/man_front"
android:layout_below="@+id/tv" />
</RelativeLayout></span></span>也有一点须要注意：
须要将adjustViewBounds属性设置为true。这样会调整ImageView的界限来保持图像纵横比不变
demo下载链接：http://download.csdn.net/detail/zxm317122667/9000969
