我开始学习 Android 中的位图和简单图形。我对此有点陌生，所以我仍在努力掌握这些概念。我下面的代码来自一个教程。它适用于位图和可绘制。我让它显示一个三角形的图像。但我有几个问题： 首先：三角形的图像显示 - 但它的底部延伸到屏幕底部。我该如何解决？第二：如何在屏幕中心显示三角形？
我的代码（取自 vogella.com）：
可绘制类：
public class MyRoundCornerDrawable extends Drawable {
private Paint paint;
public MyRoundCornerDrawable(Bitmap bitmap){
BitmapShader shader;
shader = new BitmapShader(bitmap, Shader.TileMode.CLAMP,
Shader.TileMode.CLAMP);
paint = new Paint();
paint.setAntiAlias(true);
paint.setShader(shader);
}
@Override
public void draw(Canvas canvas) {
int height = getBounds().height();
int width = getBounds().width();
RectF rect = new RectF(0.0f, 0.0f, width, height);
canvas.drawRoundRect(rect, 15, 15, paint);
}
@Override
public int getOpacity() {
return 255;
}
@Override
public void setAlpha(int alpha) {
}
@Override
public void setColorFilter(ColorFilter arg0) {
}
}
主要活动
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ImageView button = (ImageView) findViewById(R.id.image);
InputStream resource = getResources().openRawResource(R.drawable.triangle);
Bitmap bitmap = BitmapFactory.decodeStream(resource);
button.setBackground(new MyRoundCornerDrawable(bitmap));
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
和 XML：
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<ImageView
android:id="@+id/image"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:contentDescription="TODO" />