我们在开发过程中经常会遇到这样的布局设计：文字左边一个图标 ,常用的做法是用一个RelativeLayout包裹一个ImageView和一个TextView，然后设置各自都垂直居中，如下：
<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="wrap_content" android:padding="20dp"> <ImageView android:id="@+id/img" android:layout_width="wrap_content" android:layout_height="wrap_content" android:src="@mipmap/singing_like" android:layout_centerVertical="true" /> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginLeft="3dp" android:layout_toRightOf="@+id/img" android:text="居中处理" android:textColor="#000000" android:textSize="12sp" android:layout_centerVertical="true" /> </RelativeLayout>
这样我们需要用到三个控件，导致的结果是布局变得复杂，并且影响渲染效率，所以可以考虑对原本的TextView进行改造处理，实现一个控件就可以达到想要的效果，如下：
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.drawable.Drawable;
import android.support.annotation.Nullable;
import android.support.v7.widget.AppCompatTextView;
import android.util.AttributeSet;
import com.octvision.liuzhou.park.R;
public class TextViewDrawable extends AppCompatTextView {
private int drawableLeftWidth, drawableTopWidth, drawableRightWidth, drawableBottomWidth;
private int drawableLeftHeight, drawableTopHeight, drawableRightHeight, drawableBottomHeight;
private boolean isAliganCenter = true;
private boolean isDwMath_content = false;
private int mWidth, mHeight;
public TextViewDrawable(Context context) {
this(context, null);
}
public TextViewDrawable(Context context, @Nullable AttributeSet attrs) {
this(context, attrs, 0);
}
public TextViewDrawable(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
initView(context, attrs, defStyleAttr);
}
private void initView(Context context, AttributeSet attrs, int defStyleAttr) {
TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.TextViewDrawable);
drawableLeftWidth = typedArray.getDimensionPixelSize(R.styleable.TextViewDrawable_drawableLeftWidth, 0);
drawableTopWidth = typedArray.getDimensionPixelSize(R.styleable.TextViewDrawable_drawableTopWidth, 0);
drawableRightWidth = typedArray.getDimensionPixelSize(R.styleable.TextViewDrawable_drawableRightWidth, 0);
drawableBottomWidth = typedArray.getDimensionPixelSize(R.styleable.TextViewDrawable_drawableBottomWidth, 0);
drawableLeftHeight = typedArray.getDimensionPixelSize(R.styleable.TextViewDrawable_drawableLeftHeight, 0);
drawableTopHeight = typedArray.getDimensionPixelSize(R.styleable.TextViewDrawable_drawableTopHeight, 0);
drawableRightHeight = typedArray.getDimensionPixelSize(R.styleable.TextViewDrawable_drawableRightHeight, 0);
drawableBottomHeight = typedArray.getDimensionPixelSize(R.styleable.TextViewDrawable_drawableBottomHeight, 0);
isAliganCenter = typedArray.getBoolean(R.styleable.TextViewDrawable_isAliganCenter, true);
typedArray.recycle();
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
mWidth = w;
mHeight = h;
Drawable[] drawables = getCompoundDrawables();
Drawable drawableLeft = drawables[0];
Drawable drawableTop = drawables[1];
Drawable drawableRight = drawables[2];
Drawable drawableBottom = drawables[3];
if (drawableLeft != null) {
setDrawable(drawableLeft, 0, drawableLeftWidth, drawableLeftHeight);
}
if (drawableTop != null) {
setDrawable(drawableTop, 1, drawableTopWidth, drawableTopHeight);
}
if (drawableRight != null) {
setDrawable(drawableRight, 2, drawableRightWidth, drawableRightHeight);
}
if (drawableBottom != null) {
setDrawable(drawableBottom, 3, drawableBottomWidth, drawableBottomHeight);
}
this.setCompoundDrawables(drawableLeft, drawableTop, drawableRight, drawableBottom);
}
private void setDrawable(Drawable drawable, int tag, int drawableWidth, int drawableHeight) {
//获取图片实际长宽
int width = drawableWidth == 0 ? drawable.getIntrinsicWidth() : drawableWidth;
int height = drawableHeight == 0 ? drawable.getIntrinsicHeight() : drawableHeight;
int left = 0, top = 0, right = 0, bottom = 0;
int diffSize = Math.abs((int) getTextSize() - height);
switch (tag) {
case 0:
case 2:
left = 0;
top = isAliganCenter ? -getLineCount() * getLineHeight() / 2 + getLineHeight() / 2 + diffSize / 2 : 0;
right = width;
bottom = top + height;
break;
case 1:
left = isAliganCenter ? 0 : -mWidth / 2 + width / 2;
top = 0;
right = left + width;
bottom = top + height;
break;
}
drawable.setBounds(left, top, right, bottom);
}
}为了同时可以在布局中控制drawable的大小，所以添加了一些其它的属性：
<?xml version="1.0" encoding="utf-8"?> <resources> <declare-styleable name="TextViewDrawable"> <attr name="drawableLeftWidth" format="dimension" /> <attr name="drawableTopWidth" format="dimension" /> <attr name="drawableRightWidth" format="dimension" /> <attr name="drawableLeftHeight" format="dimension" /> <attr name="drawableTopHeight" format="dimension" /> <attr name="drawableRightHeight" format="dimension" /> <attr name="drawableBottomHeight" format="dimension" /> <attr name="drawableBottomWidth" format="dimension" /> <attr name="isAliganCenter" format="boolean" /> </declare-styleable> </resources>