Android仿微信朋友圈点击加号添加图片功能

本文为大家分享了类似微信朋友圈，点击+号图片，可以加图片功能，供大家参考，具体内容如下

xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginTop="40dp"
android:orientation="vertical" >
<com.sw.demo.widget.NinePhotoView
  android:id="@+id/photoview"
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  app:ninephoto_hspace="10dp"
  app:ninephoto_vspace="10dp"
  app:rainbowbar_color="@android:color/holo_blue_bright" >
</com.sw.demo.widget.NinePhotoView>

NinePhotoView.java

public class NinePhotoView extends ViewGroup {
public static final int MAX_PHOTO_NUMBER = 9;
private int[] constImageIds = { R.drawable.girl_0, R.drawable.girl_1,
   R.drawable.girl_2, R.drawable.girl_3, R.drawable.girl_4,
   R.drawable.girl_5, R.drawable.girl_6, R.drawable.girl_7,
   R.drawable.girl_8 };
// horizontal space among children views
int hSpace = Utils.dpToPx(10, getResources());
// vertical space among children views
int vSpace = Utils.dpToPx(10, getResources());
// every child view width and height.
int childWidth = 0;
int childHeight = 0;
// store images res id
ArrayList<integer> mImageResArrayList = new ArrayList<integer>(9);
private View addPhotoView;
public NinePhotoView(Context context) {
 super(context);
}
public NinePhotoView(Context context, AttributeSet attrs) {
 this(context, attrs, 0);
}
public NinePhotoView(Context context, AttributeSet attrs, int defStyle) {
 super(context, attrs, defStyle);
 TypedArray t = context.obtainStyledAttributes(attrs,
     R.styleable.NinePhotoView, 0, 0);
 hSpace = t.getDimensionPixelSize(
     R.styleable.NinePhotoView_ninephoto_hspace, hSpace);
 vSpace = t.getDimensionPixelSize(
     R.styleable.NinePhotoView_ninephoto_vspace, vSpace);
 t.recycle();
 addPhotoView = new View(context);
 addView(addPhotoView);
 mImageResArrayList.add(new integer());
}

Measure

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
 int rw = MeasureSpec.getSize(widthMeasureSpec);
 int rh = MeasureSpec.getSize(heightMeasureSpec);
 childWidth = (rw - 2 * hSpace) / 3;
 childHeight = childWidth;
 int childCount = this.getChildCount();
 for (int i = 0; i < childCount; i++) {
   View child = this.getChildAt(i);
   //this.measureChild(child, widthMeasureSpec, heightMeasureSpec);
   LayoutParams lParams = (LayoutParams) child.getLayoutParams();
   lParams.left = (i % 3) * (childWidth + hSpace);
   lParams.top = (i / 3) * (childWidth + vSpace);
 }
 int vw = rw;
 int vh = rh;
 if (childCount < 3) {
   vw = childCount * (childWidth + hSpace);
 }
 vh = ((childCount + 3) / 3) * (childWidth + vSpace);
 setMeasuredDimension(vw, vh);
}

　　我们的子View三个一排，而且都是正方形，所以我们上面通过循环很好去得到所有子View的位置，注意我们上面把子View的左上角坐标存储到我们自定义的LayoutParams 的left和top二个字段中，Layout阶段会使用，最后我们算得整个ViewGroup的宽高，调用setMeasuredDimension设置。　　

Layout

@Override
protected void onLayout(boolean arg0, int arg1, int arg2, int arg3, int arg4) {
 int childCount = this.getChildCount();
 for (int i = 0; i < childCount; i++) {
   View child = this.getChildAt(i);
   LayoutParams lParams = (LayoutParams) child.getLayoutParams();
   child.layout(lParams.left, lParams.top, lParams.left + childWidth,
       lParams.top + childHeight);
   if (i == mImageResArrayList.size() - 1 && mImageResArrayList.size() != MAX_PHOTO_NUMBER) {
     child.setBackgroundResource(R.drawable.add_photo);
     child.setOnClickListener(new View.OnClickListener() {
       @Override
       public void onClick(View arg0) {
         addPhotoBtnClick();
       }
     });
   }else {
     child.setBackgroundResource(constImageIds[i]);
     child.setOnClickListener(null);
   }
 }
}
public void addPhoto() {
 if (mImageResArrayList.size() < MAX_PHOTO_NUMBER) {
   View newChild = new View(getContext());
   addView(newChild);
   mImageResArrayList.add(new integer());
   requestLayout();
   invalidate();
 }
}
public void addPhotoBtnClick() {
 final CharSequence[] items = { "Take Photo", "Photo from gallery" };
 AlertDialog.Builder builder = new AlertDialog.Builder(getContext());
 builder.setItems(items, new DialogInterface.OnClickListener() {
   @Override
   public void onClick(DialogInterface arg0, int arg1) {
     addPhoto();
   }
 });
 builder.show();
}

　　最核心的就是调用layout方法，根据我们measure阶段获得的LayoutParams中的left和top字段，也很好对每个子View进行位置排列。然后判断在图片未达到最大值9张时，默认最后一张是+号图片，然后设置点击事件，弹出对话框供用户选择操作。

Draw

不需要重写，使用ViewGroup默认实现即可。

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