自定义view
画矩形
canvas.drawRect(left, top, right, bottom, paint);
left/top：该view的左上顶点到父容器左边和顶端的距离
right/bottom：该view的右下顶点到父容器左边和顶端的距离写字
Rects bounds = new Rects();
mPaint.setColor(mColorText);
mPaint.setTextSize(mSizeText);
mPaint.setTextAlign(Paint.Align.CENTER);
mPaint.getTextBounds(text, 0, text.length(), bounds);
float x = width / 2;
float y = -bounds.centerY() + childHeight / 2 + i * childHeight;
canvas.drawText(text, x, y, mPaint);
当text为居中对齐时，centerX和centerY是该字的正中心，以text的左下角为原点，故而centerY为-sizeOfText/2。
- 自定义属性
attrs.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="LetterIndex">
<attr name="color_text" format="color" />
<attr name="color_index_bg" format="color" />
</declare-styleable>
</resources>
MyView.java
AttributeSet attrs = ***;
TypedArray arr = context.obtainStyledAttributes(attrs, R.styleable.LetterIndex);
mColorText = arr.getColor(R.styleable.LetterIndex_color_text, 0x52000000);
注意默认值可以为int数字，但是需为0x开头八位数字，前两位表示透明度
main_act.xml
<com.text.MyView
***
app:color_text = "#003903"
/>
- 对外预留onClick监听接口
MyView.java
//定义
private onIndexClickListener mClickListener;
public interface onIndexClickListener{
void onIndexClick(int chooseId);
}
public void setOnIndexClickListener(onIndexClickListener listener){
this.mOnIndexClick = listener;
}
//使用，在需要监听的动作发生时调用该方法
mClickListener.onIndexClick(mChooseId);
MainAct.java
mView.setOnIndexClickListener(new LetterIndex.onIndexClickListener() {
@Override
public void onIndexClick(int chooseId) {
Log.d("TAG", "onIndexClick: chooseid is" + chooseId);
}
});
- RecyclerView滑动事件
manager.scrollToPositionWithOffset(n, 0);
n为要滑到顶端的position
