Android:Renderscript

lastmod 2018-08-17created 2014-02-1332 edits

RenderScript is a new API targeted at high-performance 3D rendering and compute operations. The goal of RenderScript is to give Android developers a high-performance API obtained at a low level. It is aimed at developers who are comfortable working down to the machine level to optimize the performance of their applications. RenderScript provides developers with three primary tools: a simple hardware-accelerated 3D rendering API, a developer-friendly compute API similar to CUDA, and a language similar to C99.

Using the RenderScript Support Library APIs

In order to use the Support Library RenderScript APIs, you must configure your development environment to be able to access them. The following Android SDK tools are required for using these APIs:

Android SDK Tools revision 22.2 or higher
Android SDK Build-tools revision 18.1.0 or higher
You can check and update the installed version of these tools in the Android SDK Manager.

Note: Use of Support Library RenderScript APIs is not currently supported with Android Studio or Gradle-based builds.

RenderScript APIs in Eclipse

To use the Support Library RenderScript APIs in Eclipse:
Make sure you have the required Android SDK version and Build Tools version installed.
Open the project.properties file in the root folder of your application project.
Add the following lines to the file:

renderscript.target=18
renderscript.support.mode=true
sdk.buildtools=18.1.0

In your application classes that use RenderScript, add an import for the Support Library classes:

import android.support.v8.renderscript.*;

project.properties settings list

The project.properties settings listed above control specific behavior in the Android build process:

renderscript.target: Specifies the bytecode version to be generated. We recommend you set this value the highest available API level and set renderscript.support.mode to true. Valid values for this setting are any integer value from 11 to the most recently released API level. If your minimum SDK version specified in your application manifest is set to a higher value, this value is ignored and the target value is set to the minimum SDK version.
renderscript.support.mode: Specifies that the generated bytecode should fall back to a compatible version if the device it is running on does not support the target version.
sdk.buildtools: The version of the Android SDK build tools to use. This value should be set to 18.1.0 or higher. If this option is not specified, the highest installed build tools version is used. You should always set this value to ensure the consistency of builds across development machines with different configurations.

APIs & Implement detail

If you want to use the RenderScript Support Library in your app, there are a few things you should know.

The RenderScript Support Library supports most of the native RenderScript API features supported at and after the API level. Notable exceptions are Allocation.USAGE_IO_INPUT and Allocation.USAGE_IO_OUTPUT.
These are currently not supported by the RenderScript Support Library.
On 4.3 and later, RenderScript applications can run on the processors supported by the device, whereas on Android 4.2 and earlier devices, RenderScript applications run entirely on the CPU.
(Note: GPU execution is supported on some devices even on Android 4.3, such as the Nexus 10.)
Because the Support Library versions of scripts are precompiled to support all possible platforms, compiler optimization is limited compared to Android 4.3, which compiles at runtime, and there is a corresponding performance penalty.

Print Logcat

To print log messages from RenderScript, use a function like the following.

void printLog()
{
    rsDebug("[RenderScript] testPreConditionForIntro() call.", 0);
}

Sample code

The simplest RenderScript example

mono.rs, the RenderScript input

// mono.rs
#pragma version(1)
#pragma rs java_package_name(com.example.renderscriptsample)

float3 gMonoMult = {0.2125, 0.7154, 0.0721};

void root(const uchar4 *v_in, uchar4 *v_out) {
    float4 f4 = rsUnpackColor8888(*v_in);
    float3 mono = dot(f4.rgb, gMonoMult);
    *v_out = rsPackColorTo8888(mono);
}

MainActivity.java, which implements the Android screen (Activity)

package com.example.renderscriptsample;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;

// import android.renderscript.Allocation;
// import android.renderscript.RenderScript;
import android.support.v8.renderscript.Allocation;
import android.support.v8.renderscript.RenderScript;

import android.view.Menu;
import android.widget.ImageView;

public class MainActivity extends Activity {
    // RenderScript
    private RenderScript mRS;
    private Allocation mInAllocation;
    private Allocation mOutAllocation;
    private ScriptC_mono mScript;

    private Bitmap loadBitmap(int resource) {
        final BitmapFactory.Options options = new BitmapFactory.Options();
        options.inPreferredConfig = Bitmap.Config.ARGB_8888;
        return BitmapFactory.decodeResource(getResources(), resource, options);
    }

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

        // bitmap load
        final Bitmap bm = loadBitmap(R.drawable.data);
        final Bitmap bmOut = Bitmap.createBitmap(bm.getWidth(), bm.getHeight(), bm.getConfig());

        // renderscript init
        mRS = RenderScript.create(this);
        mInAllocation = Allocation.createFromBitmap(mRS, bm, Allocation.MipmapControl.MIPMAP_NONE, Allocation.USAGE_SCRIPT);
        mOutAllocation = Allocation.createFromBitmap(mRS, bm, Allocation.MipmapControl.MIPMAP_NONE, Allocation.USAGE_SCRIPT);
        mScript = new ScriptC_mono(mRS, getResources(), R.raw.mono);

        // renderscript run
        mScript.forEach_root(mInAllocation, mOutAllocation);
        mOutAllocation.copyTo(bmOut);

        // set output bitmap
        final ImageView iv = (ImageView) findViewById(R.id.imageView1);
        iv.setImageBitmap(bmOut);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }
}

RenderScript Animation

Building on the example above, the following example uses ValueAnimator to update the Bitmap of an ImageView.

// set output bitmap
final ImageView iv = (ImageView) findViewById(R.id.activity_main__logo_icon_custom_bg);
iv.setImageBitmap(bmOut);
// ...
ValueAnimator ani = ValueAnimator.ofFloat(0.0f, 360.0f);
ani.setDuration(3000);
ani.setRepeatCount(200);
ani.setInterpolator(new AccelerateDecelerateInterpolator());
ani.addUpdateListener(new AnimatorUpdateListener() {
    @Override
    public void onAnimationUpdate(ValueAnimator animation) {
        float val = (Float) animation.getAnimatedValue();
        int rgba = Color.HSVToColor(new float[] {val, 1.0f, 1.0f});

        float r = (float)((rgba >> 16) & 0xFF) / 255.0f;
        float g = (float)((rgba >>  8) & 0xFF) / 255.0f;
        float b = (float)( rgba        & 0xFF) / 255.0f;

        mScript.set_g_add(new Float4(r, g, b, 1.0f));
        mScript.forEach_root(mInAllocation, mOutAllocation);
        mOutAllocation.copyTo(bmOut);
        iv.setImageBitmap(bmOut);
    }
});
ani.start();

The RenderScript used by the code above is as follows.
It changes every color whose Alpha value is not 0 in the Bitmap passed in as v_in.

float4 g_add = 0.0f;
/// @brief RenderScript Entry point.
void root(const uchar4 * v_in, uchar4 * v_out)
{
    // rsDebug("[RenderScript] test 1 call.", 0);
    float4 f4 = rsUnpackColor8888(*v_in);
    if (f4.w != 0) {
        f4 = g_add;
        // rsDebug("[RenderScript] test 2 call.", f4);
    }

    *v_out = rsPackColorTo8888(f4);
}

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References

Beginning_Android_RenderScript.pdf ↩
Sample Download: Renderscript-example-Gravity-r2.zip ↩
RenderScript_android_parallel_programming.pdf ↩
Designing_Apps_for_XOOM_pt2.pdf ↩
Blog.iangclifton_-RenderScript1-_Basics_Tutorial.pdf ↩
Blog.iangclifton_-RenderScript2-_Interaction.pdf ↩
RenderScript_Step4_(jp)_rsgBindTexture.pdf ↩
RenderScript_-_Page_flip.pdf ↩
RenderScript_Support_For_All_Double_Encore.pdf ↩
Open_Expert_Group_-_RenderScript.pdf ↩
RenderScript_Real_time_image_processing.pdf ↩
RSRTImgProc-master-52df27a126e5d3f1d4a32b99ce0a94d05a86cbad.tar.gz ↩
RenderScriptDemos-master-70307a646cb8f4192d292ff737c22b2dc5aed16c.tar.gz ↩
Edu4android.com_-_RenderScript.pdf ↩

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