Android example source code file (SpriteTextRenderer.java)

This example Android source code file (SpriteTextRenderer.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

android, bytebuffer, context, drawing, eglconfig, floatbuffer, graphics, io, labelmaker, nio, numericsprite, opengl, paint, projector, sample_factor, sample_period_frames, shortbuffer, spritetextrenderer, triangle, verts

The SpriteTextRenderer.java Android example source code

/*
 * Copyright (C) 2008 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.example.android.apis.graphics.spritetext;

import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import java.nio.ShortBuffer;

import javax.microedition.khronos.egl.EGL10;
import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Paint;
import android.opengl.GLSurfaceView;
import android.opengl.GLU;
import android.opengl.GLUtils;
import android.os.SystemClock;

import com.example.android.apis.R;

public class SpriteTextRenderer implements GLSurfaceView.Renderer{

    public SpriteTextRenderer(Context context) {
        mContext = context;
        mTriangle = new Triangle();
        mProjector = new Projector();
        mLabelPaint = new Paint();
        mLabelPaint.setTextSize(32);
        mLabelPaint.setAntiAlias(true);
        mLabelPaint.setARGB(0xff, 0x00, 0x00, 0x00);
    }

    public void onSurfaceCreated(GL10 gl, EGLConfig config) {
        /*
         * By default, OpenGL enables features that improve quality
         * but reduce performance. One might want to tweak that
         * especially on software renderer.
         */
        gl.glDisable(GL10.GL_DITHER);

        /*
         * Some one-time OpenGL initialization can be made here
         * probably based on features of this particular context
         */
        gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT,
                GL10.GL_FASTEST);

        gl.glClearColor(.5f, .5f, .5f, 1);
        gl.glShadeModel(GL10.GL_SMOOTH);
        gl.glEnable(GL10.GL_DEPTH_TEST);
        gl.glEnable(GL10.GL_TEXTURE_2D);

        /*
         * Create our texture. This has to be done each time the
         * surface is created.
         */

        int[] textures = new int[1];
        gl.glGenTextures(1, textures, 0);

        mTextureID = textures[0];
        gl.glBindTexture(GL10.GL_TEXTURE_2D, mTextureID);

        gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER,
                GL10.GL_NEAREST);
        gl.glTexParameterf(GL10.GL_TEXTURE_2D,
                GL10.GL_TEXTURE_MAG_FILTER,
                GL10.GL_LINEAR);

        gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_S,
                GL10.GL_CLAMP_TO_EDGE);
        gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_T,
                GL10.GL_CLAMP_TO_EDGE);

        gl.glTexEnvf(GL10.GL_TEXTURE_ENV, GL10.GL_TEXTURE_ENV_MODE,
                GL10.GL_REPLACE);

        InputStream is = mContext.getResources()
                .openRawResource(R.drawable.robot);
        Bitmap bitmap;
        try {
            bitmap = BitmapFactory.decodeStream(is);
        } finally {
            try {
                is.close();
            } catch(IOException e) {
                // Ignore.
            }
        }

        GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, bitmap, 0);
        bitmap.recycle();

        if (mLabels != null) {
            mLabels.shutdown(gl);
        } else {
            mLabels = new LabelMaker(true, 256, 64);
        }
        mLabels.initialize(gl);
        mLabels.beginAdding(gl);
        mLabelA = mLabels.add(gl, "A", mLabelPaint);
        mLabelB = mLabels.add(gl, "B", mLabelPaint);
        mLabelC = mLabels.add(gl, "C", mLabelPaint);
        mLabelMsPF = mLabels.add(gl, "ms/f", mLabelPaint);
        mLabels.endAdding(gl);

        if (mNumericSprite != null) {
            mNumericSprite.shutdown(gl);
        } else {
            mNumericSprite = new NumericSprite();
        }
        mNumericSprite.initialize(gl, mLabelPaint);
    }

    public void onDrawFrame(GL10 gl) {
        /*
         * By default, OpenGL enables features that improve quality
         * but reduce performance. One might want to tweak that
         * especially on software renderer.
         */
        gl.glDisable(GL10.GL_DITHER);

        gl.glTexEnvx(GL10.GL_TEXTURE_ENV, GL10.GL_TEXTURE_ENV_MODE,
                GL10.GL_MODULATE);

        /*
         * Usually, the first thing one might want to do is to clear
         * the screen. The most efficient way of doing this is to use
         * glClear().
         */

        gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);

        /*
         * Now we're ready to draw some 3D objects
         */

        gl.glMatrixMode(GL10.GL_MODELVIEW);
        gl.glLoadIdentity();

        GLU.gluLookAt(gl, 0.0f, 0.0f, -2.5f,
                0.0f, 0.0f, 0.0f,
                0.0f, 1.0f, 0.0f);

        gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
        gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY);

        gl.glActiveTexture(GL10.GL_TEXTURE0);
        gl.glBindTexture(GL10.GL_TEXTURE_2D, mTextureID);
        gl.glTexParameterx(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_S,
                GL10.GL_REPEAT);
        gl.glTexParameterx(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_T,
                GL10.GL_REPEAT);

        long time = SystemClock.uptimeMillis() % 4000L;
        float angle = 0.090f * ((int) time);

        gl.glRotatef(angle, 0, 0, 1.0f);
        gl.glScalef(2.0f, 2.0f, 2.0f);

        mTriangle.draw(gl);

        mProjector.getCurrentModelView(gl);
        mLabels.beginDrawing(gl, mWidth, mHeight);
        drawLabel(gl, 0, mLabelA);
        drawLabel(gl, 1, mLabelB);
        drawLabel(gl, 2, mLabelC);
        float msPFX = mWidth - mLabels.getWidth(mLabelMsPF) - 1;
        mLabels.draw(gl, msPFX, 0, mLabelMsPF);
        mLabels.endDrawing(gl);

        drawMsPF(gl, msPFX);
    }

    private void drawMsPF(GL10 gl, float rightMargin) {
        long time = SystemClock.uptimeMillis();
        if (mStartTime == 0) {
            mStartTime = time;
        }
        if (mFrames++ == SAMPLE_PERIOD_FRAMES) {
            mFrames = 0;
            long delta = time - mStartTime;
            mStartTime = time;
            mMsPerFrame = (int) (delta * SAMPLE_FACTOR);
        }
        if (mMsPerFrame > 0) {
            mNumericSprite.setValue(mMsPerFrame);
            float numWidth = mNumericSprite.width();
            float x = rightMargin - numWidth;
            mNumericSprite.draw(gl, x, 0, mWidth, mHeight);
        }
    }

    private void drawLabel(GL10 gl, int triangleVertex, int labelId) {
        float x = mTriangle.getX(triangleVertex);
        float y = mTriangle.getY(triangleVertex);
        mScratch[0] = x;
        mScratch[1] = y;
        mScratch[2] = 0.0f;
        mScratch[3] = 1.0f;
        mProjector.project(mScratch, 0, mScratch, 4);
        float sx = mScratch[4];
        float sy = mScratch[5];
        float height = mLabels.getHeight(labelId);
        float width = mLabels.getWidth(labelId);
        float tx = sx - width * 0.5f;
        float ty = sy - height * 0.5f;
        mLabels.draw(gl, tx, ty, labelId);
    }

    public void onSurfaceChanged(GL10 gl, int w, int h) {
        mWidth = w;
        mHeight = h;
        gl.glViewport(0, 0, w, h);
        mProjector.setCurrentView(0, 0, w, h);

        /*
        * Set our projection matrix. This doesn't have to be done
        * each time we draw, but usually a new projection needs to
        * be set when the viewport is resized.
        */

        float ratio = (float) w / h;
        gl.glMatrixMode(GL10.GL_PROJECTION);
        gl.glLoadIdentity();
        gl.glFrustumf(-ratio, ratio, -1, 1, 1, 10);
        mProjector.getCurrentProjection(gl);
    }

    private int mWidth;
    private int mHeight;
    private Context mContext;
    private Triangle mTriangle;
    private int mTextureID;
    private int mFrames;
    private int mMsPerFrame;
    private final static int SAMPLE_PERIOD_FRAMES = 12;
    private final static float SAMPLE_FACTOR = 1.0f / SAMPLE_PERIOD_FRAMES;
    private long mStartTime;
    private LabelMaker mLabels;
    private Paint mLabelPaint;
    private int mLabelA;
    private int mLabelB;
    private int mLabelC;
    private int mLabelMsPF;
    private Projector mProjector;
    private NumericSprite mNumericSprite;
    private float[] mScratch = new float[8];
}

class Triangle {
    public Triangle() {

        // Buffers to be passed to gl*Pointer() functions
        // must be direct, i.e., they must be placed on the
        // native heap where the garbage collector cannot
        // move them.
        //
        // Buffers with multi-byte datatypes (e.g., short, int, float)
        // must have their byte order set to native order

        ByteBuffer vbb = ByteBuffer.allocateDirect(VERTS * 3 * 4);
        vbb.order(ByteOrder.nativeOrder());
        mFVertexBuffer = vbb.asFloatBuffer();

        ByteBuffer tbb = ByteBuffer.allocateDirect(VERTS * 2 * 4);
        tbb.order(ByteOrder.nativeOrder());
        mTexBuffer = tbb.asFloatBuffer();

        ByteBuffer ibb = ByteBuffer.allocateDirect(VERTS * 2);
        ibb.order(ByteOrder.nativeOrder());
        mIndexBuffer = ibb.asShortBuffer();

        for (int i = 0; i < VERTS; i++) {
            for(int j = 0; j < 3; j++) {
                mFVertexBuffer.put(sCoords[i*3+j]);
            }
        }

        for (int i = 0; i < VERTS; i++) {
            for(int j = 0; j < 2; j++) {
                mTexBuffer.put(sCoords[i*3+j] * 2.0f + 0.5f);
            }
        }

        for(int i = 0; i < VERTS; i++) {
            mIndexBuffer.put((short) i);
        }

        mFVertexBuffer.position(0);
        mTexBuffer.position(0);
        mIndexBuffer.position(0);
    }

    public void draw(GL10 gl) {
        gl.glFrontFace(GL10.GL_CCW);
        gl.glVertexPointer(3, GL10.GL_FLOAT, 0, mFVertexBuffer);
        gl.glEnable(GL10.GL_TEXTURE_2D);
        gl.glTexCoordPointer(2, GL10.GL_FLOAT, 0, mTexBuffer);
        gl.glDrawElements(GL10.GL_TRIANGLE_STRIP, VERTS,
                GL10.GL_UNSIGNED_SHORT, mIndexBuffer);
    }

    public float getX(int vertex) {
        return sCoords[3*vertex];
    }

    public float getY(int vertex) {
        return sCoords[3*vertex+1];
    }

    private final static int VERTS = 3;

    private FloatBuffer mFVertexBuffer;
    private FloatBuffer mTexBuffer;
    private ShortBuffer mIndexBuffer;
    // A unit-sided equalateral triangle centered on the origin.
    private final static float[] sCoords = {
            // X, Y, Z
            -0.5f, -0.25f, 0,
             0.5f, -0.25f, 0,
             0.0f,  0.559016994f, 0
    };
}