Tuesday, November 10, 2015

android - How to use BitmapShader

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="#ee8af5"
    >
    <TextView
        android:id="@+id/tv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="BitmapShader"
        android:textStyle="bold"
        android:textSize="90dp"
        android:fontFamily="sans-serif-condensed"
        android:textColor="#000"
        />
    <Button
        android:id="@+id/btn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Apply BitmapShader"
        android:layout_alignParentBottom="true"
        android:layout_alignParentRight="true"
        />
</RelativeLayout>
MainActivity.java

package com.cfsuman.me.androidcode;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.BitmapShader;
import android.graphics.Shader;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.Window;
import android.widget.Button;
import android.widget.RelativeLayout;
import android.widget.TextView;


public class MainActivity extends AppCompatActivity {
    private Context mContext;
    private RelativeLayout mRL;
    private TextView mTV;
    private Button mBTN;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        requestWindowFeature(Window.FEATURE_ACTION_BAR);
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Get the application context
        mContext = getApplicationContext();

        // Get the widgets reference from XML layout
        mRL = (RelativeLayout) findViewById(R.id.rl);
        mTV = (TextView) findViewById(R.id.tv);
        mBTN = (Button) findViewById(R.id.btn);

        // Set a click listener for Button widget
        mBTN.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                /*
                    BitmapFactory
                        Creates Bitmap objects from various sources, including files, streams,
                        and byte-arrays.

                    public static Bitmap decodeResource (Resources res, int id)
                        Synonym for decodeResource(Resources, int, android.graphics.BitmapFactory.Options)
                        with null Options.

                        Returns
                            The decoded bitmap, or null if the image could not be decoded.
                */
                Bitmap bitmap = BitmapFactory.decodeResource(getResources(),R.drawable.pattern);

                /*
                    Shader
                        Known Direct Subclasses
                        BitmapShader, ComposeShader, LinearGradient, RadialGradient, SweepGradient

                        Shader is the based class for objects that return horizontal spans of colors
                        during drawing. A subclass of Shader is installed in a Paint calling
                        paint.setShader(shader). After that any object (other than a bitmap) that is
                        drawn with that paint will get its color(s) from the shader.
                */
                /*
                    BitmapShader
                        Shader used to draw a bitmap as a texture. The bitmap can be repeated or
                        mirrored by setting the tiling mode.

                    public BitmapShader (Bitmap bitmap, Shader.TileMode tileX, Shader.TileMode tileY)
                        Call this to create a new shader that will draw with a bitmap.

                    Parameters
                        bitmap : The bitmap to use inside the shader
                        tileX : The tiling mode for x to draw the bitmap in.
                        tileY : The tiling mode for y to draw the bitmap in.
                */
                /*
                    Shader.TileMode
                        CLAMP : replicate the edge color if the shader draws outside of its original bounds
                        MIRROR : repeat the shader's image horizontally and vertically, alternating
                            mirror images so that adjacent images always seam
                        REPEAT : repeat the shader's image horizontally and vertically
                */
                Shader shader = new BitmapShader(bitmap, Shader.TileMode.REPEAT, Shader.TileMode.REPEAT);

                /*
                    public void setLayerType (int layerType, Paint paint)
                        Specifies the type of layer backing this view. The layer can be LAYER_TYPE_NONE,
                        LAYER_TYPE_SOFTWARE or LAYER_TYPE_HARDWARE.

                        A layer is associated with an optional Paint instance that controls how the
                        layer is composed on screen.

                    Parameters
                        layerType : The type of layer to use with this view, must be one of
                            LAYER_TYPE_NONE, LAYER_TYPE_SOFTWARE or LAYER_TYPE_HARDWARE
                        paint : The paint used to compose the layer. This argument is optional and
                            can be null. It is ignored when the layer type is LAYER_TYPE_NONE
                */
                /*
                    public static final int LAYER_TYPE_SOFTWARE
                        Indicates that the view has a software layer. A software layer is backed by
                        a bitmap and causes the view to be rendered using Android's software rendering
                        pipeline, even if hardware acceleration is enabled.
                */
                mTV.setLayerType(View.LAYER_TYPE_SOFTWARE, null);

                /*
                    Paint
                        The Paint class holds the style and color information about how to draw
                        geometries, text and bitmaps.
                */
                mTV.getPaint().setShader(shader);
            }
        });
    }
}
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