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="#f9f4f8" > <ImageView android:id="@+id/iv" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerInParent="true" /> <Button android:id="@+id/btn" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Draw Border" android:layout_alignParentBottom="true" android:layout_alignParentRight="true" /> </RelativeLayout> MainActivity.java
package com.cfsuman.me.androidcode; import android.content.Context; import android.content.res.Resources; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.graphics.Rect; 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; public class MainActivity extends AppCompatActivity { private Context mContext; private Resources mResources; private RelativeLayout mRelativeLayout; private Button mBTN; private ImageView mImageView; private Bitmap mBitmap; @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); mImageView = (ImageView) findViewById(R.id.iv); mBTN = (Button) findViewById(R.id.btn); // Get the bitmap resource id simpulan int bitmapResourceID =R.drawable.avatar; // Set an image to ImageView mImageView.setImageBitmap(BitmapFactory.decodeResource(mResources, bitmapResourceID)); // Set a click listener for Button widget mBTN.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { // Get the bitmap from drawable resources mBitmap = BitmapFactory.decodeResource(mResources, bitmapResourceID); // Add a border around the bitmap mBitmap = addBorderToBitmap(mBitmap, 10, Color.WHITE); // Add a border around the bitmap as shadow mBitmap = addBorderToBitmap(mBitmap, 3, Color.LTGRAY); // Set the ImageView image as drawable object mImageView.setImageBitmap(mBitmap); } }); } // Custom method to add a border around bitmap protected Bitmap addBorderToBitmap(Bitmap srcBitmap, int borderWidth, int borderColor){ // Initialize a new Bitmap to make it bordered bitmap Bitmap dstBitmap = Bitmap.createBitmap( srcBitmap.getWidth() + borderWidth*2, // Width srcBitmap.getHeight() + borderWidth*2, // Height Bitmap.Config.ARGB_8888 // Config ); /* Canvas The Canvas class holds the "draw" calls. To draw something, you need 4 basic components: A Bitmap to hold the pixels, a Canvas to host the draw calls (writing into the bitmap), a drawing primitive (e.g. Rect, Path, text, Bitmap), and a paint (to describe the colors and styles for the drawing). */ // Initialize a new Canvas instance Canvas canvas = new Canvas(dstBitmap); // Initialize a new Paint instance to draw border Paint paint = new Paint(); paint.setColor(borderColor); paint.setStyle(Paint.Style.STROKE); paint.setStrokeWidth(borderWidth); paint.setAntiAlias(true); /* Rect Rect holds four integer coordinates for a rectangle. The rectangle is represented by the coordinates of its 4 edges (left, top, right bottom). These fields can be accessed directly. Use width() and height() to retrieve the rectangle's width and height. Note: most methods do not check to see that the coordinates are sorted correctly (i.e. left <= right and top <= bottom). */ /* Rect(int left, int top, int right, int bottom) Create a new rectangle with the specified coordinates. */ // Initialize a new Rect instance /* We set left = border width /2, because android draw border in a shape by covering both inner and outer side. By padding half border size, we included full border inside the canvas. */ Rect rect = new Rect( borderWidth / 2, borderWidth / 2, canvas.getWidth() - borderWidth / 2, canvas.getHeight() - borderWidth / 2 ); /* public void drawRect (Rect r, Paint paint) Draw the specified Rect using the specified Paint. The rectangle will be filled or framed based on the Style in the paint. Parameters r : The rectangle to be drawn. paint : The paint used to draw the rectangle */ // Draw a rectangle as a border/shadow on canvas canvas.drawRect(rect,paint); /* 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) */ // Draw source bitmap to canvas canvas.drawBitmap(srcBitmap, borderWidth, borderWidth, null); /* public void recycle () Free the native object associated with this bitmap, and clear the reference to the pixel data. This will not free the pixel data synchronously; it simply allows it to be garbage collected if there are no other references. The bitmap is marked as "dead", meaning it will throw an exception if getPixels() or setPixels() is called, and will draw nothing. This operation cannot be reversed, so it should only be called if you are sure there are no further uses for the bitmap. This is an advanced call, and normally need not be called, since the normal GC process will free up this memory when there are no more references to this bitmap. */ srcBitmap.recycle(); // Return the bordered circular bitmap return dstBitmap; } } 
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