tessl/maven-com-badlogicgames-gdx--gdx-backend-gwt
GWT backend for libGDX enabling Java game development for web browsers through JavaScript compilation
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Pending
input.mddocs/
Input Handling
The GWT backend provides comprehensive input handling for mouse, keyboard, touch, and mobile device sensors through DOM event integration. It supports both desktop and mobile input patterns with web-specific optimizations.
Core Input Interfaces
GwtInput { .api }
public interface GwtInput extends Input {
// Inherits all standard Input interface methods
// Plus web-specific extensions
}DefaultGwtInput { .api }
public class DefaultGwtInput extends AbstractInput implements GwtInput {
// Keyboard input
public boolean isKeyPressed(int key);
public boolean isKeyJustPressed(int key);
// Mouse input
public int getX();
public int getY();
public int getX(int pointer);
public int getY(int pointer);
public boolean isTouched();
public boolean isTouched(int pointer);
public boolean justTouched();
public boolean isButtonPressed(int button);
public boolean isButtonJustPressed(int button);
// Mouse wheel and movement
public int getDeltaX();
public int getDeltaY();
public int getDeltaX(int pointer);
public int getDeltaY(int pointer);
// Touch and multi-touch
public float getPressure();
public float getPressure(int pointer);
// Text input
public void getTextInput(TextInputListener listener, String title, String text, String hint);
public void getTextInput(TextInputListener listener, String title, String text, String hint, OnscreenKeyboardType type);
// Virtual keyboard
public void setOnscreenKeyboardVisible(boolean visible);
public void setOnscreenKeyboardVisible(boolean visible, OnscreenKeyboardType type);
// Input processors
public void setInputProcessor(InputProcessor processor);
public InputProcessor getInputProcessor();
// Accelerometer and sensors
public float getAccelerometerX();
public float getAccelerometerY();
public float getAccelerometerZ();
public boolean isPeripheralAvailable(Peripheral peripheral);
// Gyroscope
public float getGyroscopeX();
public float getGyroscopeY();
public float getGyroscopeZ();
// Compass
public float getAzimuth();
public float getPitch();
public float getRoll();
// Rotation vector
public void getRotationMatrix(float[] matrix);
// Haptic feedback (not supported on web)
public void vibrate(int milliseconds);
public void vibrate(long[] pattern, int repeat);
public void cancelVibrate();
// Mouse cursor control
public void setCursorCatched(boolean catched);
public boolean isCursorCatched();
public void setCursorPosition(int x, int y);
// Input multiplexing
public long getCurrentEventTime();
}Sensor Support Classes
GwtSensor { .api }
public class GwtSensor extends JavaScriptObject {
// Base class for browser-based sensors
protected GwtSensor();
}GwtAccelerometer { .api }
public class GwtAccelerometer extends GwtSensor {
// Device accelerometer access through browser APIs
public static native boolean isSupported();
public static native GwtAccelerometer getInstance();
public final native float getX();
public final native float getY();
public final native float getZ();
}GwtGyroscope { .api }
public class GwtGyroscope extends GwtSensor {
// Device gyroscope access through browser APIs
public static native boolean isSupported();
public static native GwtGyroscope getInstance();
public final native float getAlpha(); // Z-axis rotation
public final native float getBeta(); // X-axis rotation
public final native float getGamma(); // Y-axis rotation
}Text Input Support
Text Input Dialog
The GWT backend provides web-compatible text input through browser dialogs:
// Basic text input
Gdx.input.getTextInput(new TextInputListener() {
@Override
public void input(String text) {
// Handle user input
System.out.println("User entered: " + text);
}
@Override
public void canceled() {
// Handle input cancellation
System.out.println("Input canceled");
}
}, "Enter Name", "", "Your name here");
// Numeric input
Gdx.input.getTextInput(new TextInputListener() {
@Override
public void input(String text) {
try {
int score = Integer.parseInt(text);
// Handle numeric input
} catch (NumberFormatException e) {
// Handle invalid input
}
}
@Override
public void canceled() {
// Handle cancellation
}
}, "High Score", "", "Enter score", OnscreenKeyboardType.NumberPad);Usage Examples
Basic Input Handling
public class InputGame implements ApplicationListener {
private InputProcessor inputProcessor;
@Override
public void create() {
inputProcessor = new InputAdapter() {
@Override
public boolean keyDown(int keycode) {
switch (keycode) {
case Input.Keys.SPACE:
// Handle spacebar press
return true;
case Input.Keys.ESCAPE:
// Handle escape key
return true;
}
return false;
}
@Override
public boolean touchDown(int screenX, int screenY, int pointer, int button) {
// Handle mouse/touch press
System.out.println("Touch at: " + screenX + ", " + screenY);
return true;
}
@Override
public boolean scrolled(float amountX, float amountY) {
// Handle mouse wheel scroll
System.out.println("Scrolled: " + amountX + ", " + amountY);
return true;
}
};
Gdx.input.setInputProcessor(inputProcessor);
}
@Override
public void render() {
// Poll-based input checking
if (Gdx.input.isKeyPressed(Input.Keys.LEFT)) {
// Move left
}
if (Gdx.input.isKeyPressed(Input.Keys.RIGHT)) {
// Move right
}
if (Gdx.input.isTouched()) {
int x = Gdx.input.getX();
int y = Gdx.input.getY();
// Handle continuous touch/drag
}
}
}Multi-Touch Support
public class MultiTouchGame implements ApplicationListener {
private static final int MAX_TOUCHES = 10;
@Override
public void render() {
// Check multiple touch points
for (int i = 0; i < MAX_TOUCHES; i++) {
if (Gdx.input.isTouched(i)) {
int x = Gdx.input.getX(i);
int y = Gdx.input.getY(i);
float pressure = Gdx.input.getPressure(i);
// Handle individual touch point
handleTouch(i, x, y, pressure);
}
}
}
private void handleTouch(int pointer, int x, int y, float pressure) {
// Handle specific touch point
}
}Mobile Sensor Input
public class SensorGame implements ApplicationListener {
private boolean accelerometerAvailable;
private boolean gyroscopeAvailable;
@Override
public void create() {
// Check sensor availability
accelerometerAvailable = Gdx.input.isPeripheralAvailable(Input.Peripheral.Accelerometer);
gyroscopeAvailable = Gdx.input.isPeripheralAvailable(Input.Peripheral.Gyroscope);
System.out.println("Accelerometer: " + accelerometerAvailable);
System.out.println("Gyroscope: " + gyroscopeAvailable);
}
@Override
public void render() {
if (accelerometerAvailable) {
float accelX = Gdx.input.getAccelerometerX();
float accelY = Gdx.input.getAccelerometerY();
float accelZ = Gdx.input.getAccelerometerZ();
// Use accelerometer for tilt controls
handleTilt(accelX, accelY, accelZ);
}
if (gyroscopeAvailable) {
float gyroX = Gdx.input.getGyroscopeX();
float gyroY = Gdx.input.getGyroscopeY();
float gyroZ = Gdx.input.getGyroscopeZ();
// Use gyroscope for rotation controls
handleRotation(gyroX, gyroY, gyroZ);
}
}
private void handleTilt(float x, float y, float z) {
// Implement tilt-based controls
}
private void handleRotation(float x, float y, float z) {
// Implement rotation-based controls
}
}Keyboard Input with Key Codes
public class KeyboardGame implements ApplicationListener {
@Override
public void create() {
Gdx.input.setInputProcessor(new InputAdapter() {
@Override
public boolean keyDown(int keycode) {
switch (keycode) {
case Input.Keys.W:
case Input.Keys.UP:
// Move up
return true;
case Input.Keys.S:
case Input.Keys.DOWN:
// Move down
return true;
case Input.Keys.A:
case Input.Keys.LEFT:
// Move left
return true;
case Input.Keys.D:
case Input.Keys.RIGHT:
// Move right
return true;
case Input.Keys.ENTER:
// Confirm action
return true;
case Input.Keys.ESCAPE:
// Cancel/menu
return true;
}
return false;
}
});
}
}Mouse Button Handling
public class MouseGame implements ApplicationListener {
@Override
public void create() {
Gdx.input.setInputProcessor(new InputAdapter() {
@Override
public boolean touchDown(int screenX, int screenY, int pointer, int button) {
switch (button) {
case Input.Buttons.LEFT:
// Primary action (left click or touch)
handlePrimaryAction(screenX, screenY);
return true;
case Input.Buttons.RIGHT:
// Secondary action (right click)
handleSecondaryAction(screenX, screenY);
return true;
case Input.Buttons.MIDDLE:
// Middle mouse button
handleMiddleAction(screenX, screenY);
return true;
}
return false;
}
@Override
public boolean mouseMoved(int screenX, int screenY) {
// Handle mouse movement (no buttons pressed)
return true;
}
@Override
public boolean touchDragged(int screenX, int screenY, int pointer) {
// Handle drag operations
return true;
}
});
}
private void handlePrimaryAction(int x, int y) {
// Left click or touch handling
}
private void handleSecondaryAction(int x, int y) {
// Right click handling (context menu, etc.)
}
private void handleMiddleAction(int x, int y) {
// Middle mouse button handling
}
}Web-Specific Input Considerations
Browser Input Limitations
// Some input features have web-specific behavior:
// Cursor catching (pointer lock) requires user permission
public void enablePointerLock() {
if (!Gdx.input.isCursorCatched()) {
// Must be called in response to user interaction
Gdx.input.setCursorCatched(true);
}
}
// Vibration is not supported in browsers
public void tryVibrate() {
if (Gdx.input.isPeripheralAvailable(Input.Peripheral.Vibrator)) {
Gdx.input.vibrate(100); // Will not work on web
}
}
// Some key events may be captured by browser
// (F11 for fullscreen, Ctrl+R for refresh, etc.)Input Event Handling Order
// Input events in GWT backend follow this order:
// 1. InputProcessor methods (if set)
// 2. Input polling methods (isKeyPressed, isTouched, etc.)
public class InputOrderExample implements ApplicationListener {
@Override
public void create() {
// Event-based input (immediate response)
Gdx.input.setInputProcessor(new InputAdapter() {
@Override
public boolean keyDown(int keycode) {
// Handles key press immediately
return true; // Return true to consume event
}
});
}
@Override
public void render() {
// Poll-based input (checked each frame)
if (Gdx.input.isKeyPressed(Input.Keys.SPACE)) {
// Checked continuously while key is held
}
}
}Install with Tessl CLI
npx tessl i tessl/maven-com-badlogicgames-gdx--gdx-backend-gwt