android - How to draw a Bitmap on a Canvas

activity_main.xml 
 <?xml version="1.0" encoding="utf-8"?> <RelativeLayout     xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:tools="http://schemas.android.com/tools"     android:id="@+id/rl"     android:layout_width="match_parent"     android:layout_height="match_parent"     android:padding="16dp"     tools:context=".MainActivity"     android:background="#b4aba7"     >     <ImageView         android:id="@+id/iv"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         />     <Button         android:id="@+id/btn"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:text="Draw Bitmap"         android:layout_alignParentRight="true"         android:layout_alignParentEnd="true"         android:layout_alignParentBottom="true"         /> </RelativeLayout>
MainActivity.java 
 package com.cfsuman.me.androidcode;  import android.content.Context; import android.content.res.Resources; import android.graphics.BitmapFactory; import android.graphics.Color; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.View; import android.widget.Button; import android.widget.ImageView; import android.widget.RelativeLayout; import android.graphics.Canvas; import android.graphics.Bitmap;   public class MainActivity extends AppCompatActivity {     private Context mContext;     private Resources mResources;     private RelativeLayout mRelativeLayout;     private Button mButton;     private ImageView mImageView;      @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);          // Get the application context         mContext = getApplicationContext();          // Get the Resources         mResources = getResources();          // Get the widgets reference from XML layout         mRelativeLayout = (RelativeLayout) findViewById(R.id.rl);         mButton = (Button) findViewById(R.id.btn);         mImageView = (ImageView) findViewById(R.id.iv);          // Set a click listener for Button widget         mButton.setOnClickListener(new View.OnClickListener() {             @Override             public void onClick(View view) {                 // Bitmap to draw on the canvas                 Bitmap bitmap = BitmapFactory.decodeResource(                         mResources,                         R.drawable.avatar_boy_blue                 );                  // Define an offset value between canvas and bitmap                 int offset = 50;                  // Initialize a new Bitmap to hold the source bitmap                 Bitmap dstBitmap = Bitmap.createBitmap(                         bitmap.getWidth() + offset * 2, // Width                         bitmap.getHeight() + offset * 2, // Height                         Bitmap.Config.ARGB_8888 // Config                 );                  // Initialize a new Canvas instance                 Canvas canvas = new Canvas(dstBitmap);                  // Draw a solid color on the canvas as background                 canvas.drawColor(Color.LTGRAY);                  /*                     public void drawBitmap (Bitmap bitmap, float left, float top, Paint paint)                         Draw the specified bitmap, with its top/left corner at (x,y), using the                         specified paint, transformed by the current matrix.                          Note: if the paint contains a maskfilter that generates a mask which extends                         beyond the bitmap's original width/height (e.g. BlurMaskFilter), then the                         bitmap will be drawn as if it were in a Shader with CLAMP mode. Thus the                         color outside of the original width/height will be the edge color replicated.                          If the bitmap and canvas have different densities, this function will take                         care of automatically scaling the bitmap to draw at the same density                         as the canvas.                      Parameters                         bitmap : The bitmap to be drawn                         left : The position of the left side of the bitmap being drawn                         top : The position of the top side of the bitmap being drawn                         paint : The paint used to draw the bitmap (may be null)                 */                  //Finally, Draw the source bitmap on the canvas                 canvas.drawBitmap(                         bitmap, // Bitmap                         offset, // Left                         offset, // Top                         null // Paint                 );                  // Display the newly created bitmap on app interface                 mImageView.setImageBitmap(dstBitmap);             }         });     } }
More android examples

Komentar

Posting Komentar