[Android] Bitmap圖片繪製

關於Canvas和Paint的相關設定可以看這篇:

Canvas/Paint

示範

XML

xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/b1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="bitmap"
        android:text="Bitmap"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <ImageView
        android:id="@+id/ig1"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintBottom_toTopOf="@+id/b1"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.502"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

android.support.constraint.ConstraintLayout>

JAVA

public class MainActivity extends AppCompatActivity {
Bitmap bitmap;
ImageView ig1;
Canvas canvas;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ig1=(ImageView)findViewById(R.id.ig1);
    }
    public void bitmap(View v){
    bitmap=Bitmap.createBitmap(ig1.getWidth(),ig1.getHeight(),Bitmap.Config.ARGB_8888);//創建Bitmap畫布
        Paint paint = new Paint();//創建畫筆
        paint.setColor(Color.BLACK);//設置畫筆顏色
        paint.setStyle(Paint.Style.FILL);//設置中空或是填滿畫筆
        paint.setTextSize(100);//設置文字顏色
        canvas = new Canvas(bitmap);
        canvas.drawCircle(ig1.getWidth()/2, ig1.getHeight()/2, 400, paint);//繪製圓形(寬/高/元半徑/選擇畫筆)
        ig1.setImageBitmap(bitmap);//將Bitmap圖片載入ImageView元件
    }
}

展示

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