在開發(fā)過程中惦积，我們可能會經(jīng)常遇到這樣的需求樣式：
這張圖是截取京東消息通知的彈出框昔馋，我們可以看到右上方有個三角形的氣泡效果筹吐，這只是其中一種，三角形的方向還可以是上绒极、下骏令、左、右垄提。
通過截圖可以發(fā)現(xiàn)榔袋，氣泡由正三角形和圓角長方形組成，于是可以通過組合來形成三角形氣泡的效果铡俐，下面我們通過三種方式進行實現(xiàn)凰兑。
實現(xiàn)方式：
1、通過.9圖進行實現(xiàn)审丘；
2吏够、通過shape方式實現(xiàn)；
3滩报、通過自定義view的方式實現(xiàn)锅知；
實現(xiàn)邏輯：
1、通過.9圖進行實現(xiàn)
這種方式就不用說了吧脓钾，找你們UI小姐姐切一個.9圖售睹，使用即可，不過這種方式的圖片需要占一定體積哦可训。
2昌妹、通過shape方式實現(xiàn)
- 正三角形
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item>
<rotate
android:fromDegrees="45"
android:pivotX="-40%"
android:pivotY="80%">
<shape android:shape="rectangle">
<size
android:width="15dp"
android:height="15dp" />
<solid android:color="#ffffff" />
</shape>
</rotate>
</item>
</layer-list>
- 倒三角形
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item>
<rotate
android:fromDegrees="45"
android:pivotX="135%"
android:pivotY="15%">
<shape android:shape="rectangle">
<size
android:width="15dp"
android:height="15dp" />
<solid android:color="#ffffff" />
</shape>
</rotate>
</item>
</layer-list>
- 左三角形
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item>
<rotate
android:fromDegrees="-45"
android:pivotX="85%"
android:pivotY="-35%">>
<shape android:shape="rectangle">
<size
android:width="15dp"
android:height="15dp" />
<solid android:color="#ffffff" />
</shape>
</rotate>
</item>
</layer-list>
- 右三角形
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item>
<rotate
android:fromDegrees="-45"
android:pivotX="15%"
android:pivotY="135%">>
<shape android:shape="rectangle">
<size
android:width="15dp"
android:height="15dp" />
<solid android:color="#ffffff" />
</shape>
</rotate>
</item>
</layer-list>
上面就是通過shape方式實現(xiàn)各個方向的代碼，這種方式缺點比較明顯握截，如果要變化不同的角的位置需要再寫不同的布局飞崖。
3、通過自定義view的方式實現(xiàn)
由于是比較簡單這里就不講解每個怎么搞了谨胞，可以復(fù)制過去直接用
- 添加自定義屬性
<declare-styleable name="TriangleView">
<attr name="trv_color" format="color" />
<attr name="trv_direction">
<enum name="top" value="0" />
<enum name="bottom" value="1" />
<enum name="right" value="2" />
<enum name="left" value="3" />
</attr>
</declare-styleable>
- 自定義代碼文件
public class TriangleView extends View {
private static final int TOP = 0;
private static final int BOTTOM = 1;
private static final int RIGHT = 2;
private static final int LEFT = 3;
private static final int DEFUALT_WIDTH = 10;
private static final int DEFUALT_HEIGHT = 6;
private static final int DEFUALT_COLOR = R.color.FFF;
private Paint mPaint;
private int mColor;
private int mWidth;
private int mHeight;
private int mDirection;
private Path mPath;
public TriangleView(final Context context) {
this(context, null);
}
public TriangleView(Context context, @Nullable AttributeSet attrs) {
this(context, attrs, 0);
}
public TriangleView(final Context context, final AttributeSet attrs, final int defStyleAttr) {
super(context, attrs, defStyleAttr);
init();
TypedArray typedArray = context.getTheme().obtainStyledAttributes(attrs, R.styleable.TriangleView, 0, 0);
mColor = typedArray.getColor(R.styleable.TriangleView_trv_color, ContextCompat.getColor(getContext(), DEFUALT_COLOR));
mDirection = typedArray.getInt(R.styleable.TriangleView_trv_direction, mDirection);
typedArray.recycle();
mPaint.setColor(mColor);
}
private void init() {
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setStyle(Paint.Style.FILL);
mPath = new Path();
mDirection = TOP;
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
mWidth = MeasureSpec.getSize(widthMeasureSpec);
mHeight = MeasureSpec.getSize(heightMeasureSpec);
final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
if (mWidth == 0 || widthMode != MeasureSpec.EXACTLY) {
mWidth = (int) PixelUtil.dp2px(DEFUALT_WIDTH);
}
if (mHeight == 0 || heightMode != MeasureSpec.EXACTLY) {
mHeight = (int) PixelUtil.dp2px(DEFUALT_HEIGHT);
}
setMeasuredDimension(mWidth, mHeight);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
switch (mDirection) {
case TOP:
mPath.moveTo(0, mHeight);
mPath.lineTo(mWidth, mHeight);
mPath.lineTo(mWidth / 2, 0);
break;
case BOTTOM:
mPath.moveTo(0, 0);
mPath.lineTo(mWidth / 2, mHeight);
mPath.lineTo(mWidth, 0);
break;
case RIGHT:
mPath.moveTo(0, 0);
mPath.lineTo(0, mHeight);
mPath.lineTo(mWidth, mHeight / 2);
break;
case LEFT:
mPath.moveTo(0, mHeight / 2);
mPath.lineTo(mWidth, mHeight);
mPath.lineTo(mWidth, 0);
break;
default:
break;
}
mPath.close();
canvas.drawPath(mPath, mPaint);
}
}
- 布局文件添加
<com.sjl.keeplive.triange.TriangleView
android:layout_width="10dp"
android:layout_height="6dp"
app:trv_color="@color/FFF"
app:trv_direction="top" />
通過自定義的方式可以搞定四個方向固歪，而且在代碼中也可以使用，動態(tài)添加胯努，動態(tài)改變顏色牢裳，還是比較好的方式术瓮。
到這里就完成啦.
