自定义九宫格控件NineGridLayout ,实现微信朋友圈图片九宫格显示

前言

很多时候我们都在刷微博或者微信朋友圈的时候都会看到很多图片，而这些图片的显示跟我们平时很多控件的显示方式都不一样，而且，当我们仔细去观察后就会发现，他加载的图片都是根据图片数量动态加载的，根据不同的图片数量来用不同的布局显示，如下图：



PS：图片来源于网络

当图片是4张的时候，就会形成一个2x2的正方形，除了一张的情况，另外的都是按照九宫格的方式显示和排列图片的。那么这种布局是怎么实现的呢，一开始，好多人都可能认为用原生的GridView就能搞掂，但是，却有几种特殊的情况是GridView解决不了的，例如4张图片的情况，或者1张，其实也可以根据图片的数量然后用几个不同布局的GridView来实现，不过那样的话就复杂得多了。而且处理起来很麻烦，其实，大部分的实现都是通过自定义ViewGroup来实现的，通过代码编写来设定childrenView的layout来实现这种布局，而NineGridView控件就是这么一个东西，代码其实很简单，100行就够了。

代码编写

先自定义一个View集成ViewGroup，编辑器会提示你实现OnLayout方法，实现之，这里我们动态的添加的话其实不用到OnLayout方法，自定义一个layoutChildrenView()用来为子view设定位置就行了，该方法的实现如下：

private void layoutChildrenView(){
int childrenCount = listData.size();

int singleWidth = (totalWidth - gap * (3 - 1)) / 3;
int singleHeight = singleWidth;

//根据子view数量确定高度
ViewGroup.LayoutParams params = getLayoutParams();
params.height = singleHeight * rows + gap * (rows - 1);
setLayoutParams(params);

for (int i = 0; i < childrenCount; i++) {
CustomImageView childrenView = (CustomImageView) getChildAt(i);
childrenView.setImageUrl(((Image) listData.get(i)).getUrl());
int[] position = findPosition(i);
int left = (singleWidth + gap) * position[1];
int top = (singleHeight + gap) * position[0];
int right = left + singleWidth;
int bottom = top + singleHeight;

childrenView.layout(left, top, right, bottom);
}

}

这代码里面在调用子view的layout方法的同时设定了本身ViewGroup的高度大小，因为NineGridView的高度是要根据子View的高度来确定的.
添加一个设置图片资源的接口，一般情况下我们都是用在listview来显示数据，而数据都是封装好的，这里提供一个Image封装类，接口和封装类代码如下：

public void setImagesData(List<Image> lists) {
if (lists == null || lists.isEmpty()) {
return;
}
//初始化布局
generateChildrenLayout(lists.size());
//这里做一个重用view的处理
if (listData == null) {
int i = 0;
while (i < lists.size()) {
CustomImageView iv = generateImageView();
addView(iv,generateDefaultLayoutParams());
i++;
}
} else {
int oldViewCount = listData.size();
int newViewCount = lists.size();
if (oldViewCount > newViewCount) {
removeViews(newViewCount - 1, oldViewCount - newViewCount);
} else if (oldViewCount < newViewCount) {
for (int i = 0; i < newViewCount - oldViewCount; i++) {
CustomImageView iv = generateImageView();
addView(iv,generateDefaultLayoutParams());
}
}
}
listData = lists;
layoutChildrenView();
}

Image封装类：

public class Image {
private String url;
private int width;
private int height;

public Image(String url, int width, int height) {
this.url = url;
this.width = width;
this.height = height;
L.i(toString());
}

public String getUrl() {
return url;
}

public void setUrl(String url) {
this.url = url;
}

public int getWidth() {
return width;
}

public void setWidth(int width) {
this.width = width;
}

public int getHeight() {
return height;
}

public void setHeight(int height) {
this.height = height;
}

@Override
public String toString() {

return "image---->>url="+url+"width="+width+"height"+height;
}
}

在添加数据的时候，我们要根据图片的个数来确定具体的布局情况，这个函数就是generateChildrenLayout(),实现如下：

private void generateChildrenLayout(int length) {
if (length <= 3) {
rows = 1;
columns = length;
} else if (length <= 6) {
rows = 2;
columns = 3;
if (length == 4) {
columns = 2;
}
} else {
rows = 3;
columns = 3;
}
}

这些，就是NineGridLayout的核心代码了，是不是很简单，整个类的源码如下：

public class NineGridlayout extends ViewGroup {

/**
* 图片之间的间隔
*/
private int gap = 5;
private int columns;//
private int rows;//
private List listData;
private int totalWidth;

public NineGridlayout(Context context) {
super(context);
}

public NineGridlayout(Context context, AttributeSet attrs) {
super(context, attrs);
ScreenTools screenTools=ScreenTools.instance(getContext());
totalWidth=screenTools.getScreenWidth()-screenTools.dip2px(80);
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}

@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {

}
private void layoutChildrenView(){
int childrenCount = listData.size();

int singleWidth = (totalWidth - gap * (3 - 1)) / 3;
int singleHeight = singleWidth;

//根据子view数量确定高度
ViewGroup.LayoutParams params = getLayoutParams();
params.height = singleHeight * rows + gap * (rows - 1);
setLayoutParams(params);

for (int i = 0; i < childrenCount; i++) {
CustomImageView childrenView = (CustomImageView) getChildAt(i);
childrenView.setImageUrl(((Image) listData.get(i)).getUrl());
int[] position = findPosition(i);
int left = (singleWidth + gap) * position[1];
int top = (singleHeight + gap) * position[0];
int right = left + singleWidth;
int bottom = top + singleHeight;

childrenView.layout(left, top, right, bottom);
}

}

private int[] findPosition(int childNum) {
int[] position = new int[2];
for (int i = 0; i < rows; i++) {
for (int j = 0; j < columns; j++) {
if ((i * columns + j) == childNum) {
position[0] = i;//行
position[1] = j;//列
break;
}
}
}
return position;
}

public int getGap() {
return gap;
}

public void setGap(int gap) {
this.gap = gap;
}

public void setImagesData(List<Image> lists) {
if (lists == null || lists.isEmpty()) {
return;
}
//初始化布局
generateChildrenLayout(lists.size());
//这里做一个重用view的处理
if (listData == null) {
int i = 0;
while (i < lists.size()) {
CustomImageView iv = generateImageView();
addView(iv,generateDefaultLayoutParams());
i++;
}
} else {
int oldViewCount = listData.size();
int newViewCount = lists.size();
if (oldViewCount > newViewCount) {
removeViews(newViewCount - 1, oldViewCount - newViewCount);
} else if (oldViewCount < newViewCount) {
for (int i = 0; i < newViewCount - oldViewCount; i++) {
CustomImageView iv = generateImageView();
addView(iv,generateDefaultLayoutParams());
}
}
}
listData = lists;
layoutChildrenView();
}

/**
* 根据图片个数确定行列数量
* 对应关系如下
* num	row	column
* 1	   1	1
* 2	   1	2
* 3	   1	3
* 4	   2	2
* 5	   2	3
* 6	   2	3
* 7	   3	3
* 8	   3	3
* 9	   3	3
*
* @param length
*/
private void generateChildrenLayout(int length) {
if (length <= 3) {
rows = 1;
columns = length;
} else if (length <= 6) {
rows = 2;
columns = 3;
if (length == 4) {
columns = 2;
}
} else {
rows = 3;
columns = 3;
}
}

private CustomImageView generateImageView() {
CustomImageView iv = new CustomImageView(getContext());
iv.setScaleType(ImageView.ScaleType.CENTER_CROP);
iv.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {

}
});
iv.setBackgroundColor(Color.parseColor("#f5f5f5"));
return iv;
}

}

因为微信那些图片在点击的时候是有一个灰色的蒙版的，实现起来其实很简单，我们这里在自定义一个imageview，叫做CustomImageView，复写onTouchEvent方法，在onKeyDown的时候添加一个colorfilter，然后再onKeyUp的时候clear掉，这样就实现了点击有灰色蒙版的效果，同时为了方便项目加载图片的解耦，我加载图片用了picasso这个开源库，这个开源库的地址为点击打开链接 ,具体的代码如下：

public class CustomImageView extends ImageView {
private String url;
private boolean isAttachedToWindow;

public CustomImageView(Context context, AttributeSet attrs) {
super(context, attrs);
}

public CustomImageView(Context context) {
super(context);
}

@Override
public boolean onTouchEvent(MotionEvent event) {

switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
Drawable drawable=getDrawable();
if(drawable!=null) {
drawable.mutate().setColorFilter(Color.GRAY,
PorterDuff.Mode.MULTIPLY);
}
break;
case MotionEvent.ACTION_MOVE:
break;
case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_UP:
Drawable drawableUp=getDrawable();
if(drawableUp!=null) {
drawableUp.mutate().clearColorFilter();
}
break;
}

return super.onTouchEvent(event);
}

@Override
public void onAttachedToWindow() {
isAttachedToWindow = true;
setImageUrl(url);
super.onAttachedToWindow();
}

@Override
public void onDetachedFromWindow() {
Picasso.with(getContext()).cancelRequest(this);
isAttachedToWindow = false;
setImageBitmap(null);
super.onDetachedFromWindow();
}

public void setImageUrl(String url) {
if (!TextUtils.isEmpty(url)) {
this.url = url;
if (isAttachedToWindow) {
Picasso.with(getContext()).load(url).placeholder(new ColorDrawable(Color.parseColor("#f5f5f5"))).into(this);
}
}
}
}

上面就是所以的代码了，上几张图看看效果







这个demo代码我也上传了，在我的github上面，可以到上面去下载，地址是：项目源码