Proposal For Inclusion of Robot and ParametersImpl in the Public API

[Michael Ennen]

I have created a (small) proposal (building on the work of Benjamin
Gudehaus) about moving some classes in to the public API so that TestFX (a
JavaFX UI testing framework) can continue to work with future JDK releases.
The somewhat nicely formatted proposal can be found as a Github gist:

https://gist.github.com/brcolow/26370db6cab0355186d4a1d13b30fc19

All suggested changes can be found by using Github Compare View:

https://github.com/brcolow/openjfx/compare/4ccdbbbce5234e2c5e1f4f1cb8f20430feaa53b6...master

But I have copied it to this email for convenience:

----------------------- PROPOSAL -----------------------

TestFX, the JavaFX GUI testing framework currently requires 4 (four)
classes that are part of the JDK's private API. They are:

[com.sun.glass.ui.Application](
http://hg.openjdk.java.net/openjfx/10-dev/rt/file/tip/modules/javafx.graphics/src/main/java/com/sun/glass/ui/Application.java
)
[com.sun.glass.ui.Pixels](
http://hg.openjdk.java.net/openjfx/10-dev/rt/file/tip/modules/javafx.graphics/src/main/java/com/sun/glass/ui/Pixels.java
)
[com.sun.glass.ui.Robot](
http://hg.openjdk.java.net/openjfx/10-dev/rt/file/tip/modules/javafx.graphics/src/main/java/com/sun/glass/ui/Robot.java
)
[com.sun.javafx.application.ParametersImpl](
http://hg.openjdk.java.net/openjfx/10-dev/rt/file/tip/modules/javafx.graphics/src/main/java/com/sun/javafx/application/ParametersImpl.java
)

In order to compile the project with Java 9, we use the following flags:

```sh
--add-exports javafx.graphics/com.sun.glass.ui=org.testfx
--add-exports javafx.graphics/com.sun.javafx.application=org.testfx
```

If the --add-exports flags are disabled in a future Java release TestFX
will require these four classes to be moved into the public API to
continue working.

While these classes are probably not very useful for applications to use
directly, any JavaFX application wanting to write UI tests will most likely
use TestFX and thus they will indirectly be using these classes.

JavaFX internal tests also use these classes for essentially the same
purpose (UI tests).

### Details of Usage For Each Private API Class

#### com.sun.javafx.application.ParametersImpl

##### TestFX Usage

```java
ParametersImpl parameters = new ParametersImpl(applicationArgs);
ParametersImpl.registerParameters(application, parameters);
```

The parameters are set on a constructed Application.

##### Suggested Public API Replacement

`javafx.application.Application`:

```java
/**
 * Sets the parameters for this Application.
 *
 * <p>
 * NOTE: this method should not be called from the Application constructor,
 * as it will return null. It may be called in the init() method or any
 * time after that.
 * </p>
 *
 * @param parameters the parameters to set for this Application
 */
public final Parameters setParameters(String... parameters) {
    ParametersImpl parameters = new ParametersImpl(parameters);
    ParametersImpl.registerParameters(this, parameters);
}
```

#### com.sun.glass.ui.Application

##### TestFX Usage

```java
return Application.GetApplication().createRobot();
```

The Application class is used to instantiate a Robot.

##### Suggested Public API Replacement

`javafx.application.Application`:

https://github.com/brcolow/openjfx/blob/master/modules/javafx.graphics/src/main/java/javafx/application/Application.java#L527

#### com.sun.glass.ui.Pixels

##### TestFX Usage

```java
@Override
public Image getCaptureRegion(Rectangle2D region) {
    return waitForAsyncFx(RETRIEVAL_TIMEOUT_IN_MILLIS, () -> {
        Pixels glassPixels = useRobot().getScreenCapture(
            (int) region.getMinX(), (int) region.getMinY(),
            (int) region.getWidth(), (int) region.getHeight()
        );
        return convertFromGlassPixels(glassPixels);
    });
}

private Image convertFromGlassPixels(Pixels glassPixels) {
    int width = glassPixels.getWidth();
    int height = glassPixels.getHeight();
    WritableImage image = new WritableImage(width, height);

    int bytesPerComponent = glassPixels.getBytesPerComponent();
    if (bytesPerComponent == INT_BUFFER_BYTES_PER_COMPONENT) {
        IntBuffer intBuffer = (IntBuffer) glassPixels.getPixels();
        writeIntBufferToImage(intBuffer, image);
    }

    return image;
}

private void writeIntBufferToImage(IntBuffer intBuffer,
                                   WritableImage image) {
    PixelWriter pixelWriter = image.getPixelWriter();
    double width = image.getWidth();
    double height = image.getHeight();

    for (int y = 0; y < height; y++) {
        for (int x = 0; x < width; x++) {
            int argb = intBuffer.get();
            pixelWriter.setArgb(x, y, argb);
        }
    }
}
```

Pixels is used to create a screen capture.

##### Suggested Public API Replacement

Bypass needing to expose the Pixels class to the public API by
changing the getScreenCapture method of Robot - that is, changing:

`public Pixels getScreenCapture(int x, int y, int width, int height)`

to:

`public Image getScreenCapture(int x, int y, int width, int height)`

#### com.sun.glass.ui.Robot

##### TestFX Usage

Essentially every method of Robot is used:

```
public void keyPress(int code)
public void keyRelease(int code)
public int getMouseX()
public int getMouseY()
public void mouseMove(int x, int y)
public void mousePress(int buttons)
public void mouseRelease(int buttons)
public void mouseWheel(int wheelAmt)
public int getPixelColor(int x, int y)
public Pixels getScreenCapture(int x, int y, int width, int height)
```

##### Suggested Public API Replacement

https://github.com/brcolow/openjfx/blob/master/modules/javafx.graphics/src/main/java/javafx/scene/robot/Robot.java


-- 
Michael Ennen