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Documentation Index

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In addition to event callbacks registered with GEventAttachKey and GEventAttachClick, LWXGL provides polling functions to read the current mouse and keyboard state at any point within a frame. These are useful for continuous input — e.g. smooth movement — where a callback-per-event model is too coarse. State is updated by GHandleWindowEvents, so polling before that call each frame will return the state from the previous frame.

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GQueryMouse

void GQueryMouse(int* x, int* y, int* btn)
Fills in the current cursor position and any currently held mouse button.
​
x
int*
required
Output. Set to the cursor’s current X coordinate in window pixels. Set to -1 when the cursor is outside the window.
​
y
int*
required
Output. Set to the cursor’s current Y coordinate in window pixels. Set to -1 when the cursor is outside the window.
​
btn
int*
required
Output. Set to the button currently held down (1=left, 2=middle, 3=right, 4=scroll-up, 5=scroll-down), or 0 if no button is held.
int mx, my, mbtn;
GQueryMouse(&mx, &my, &mbtn);

if (mx != -1 && my != -1) {
    printf("Cursor at (%d, %d), button held: %d\n", mx, my, mbtn);
}

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GQueryKeyboard

unsigned char* GQueryKeyboard(void)
Returns a pointer to the internal unsigned char[8] array of currently held keys. Each slot contains the character code (ASCII or LWXGL key constant) of one held key, or 0 if that slot is unused. Up to 8 simultaneous keys are tracked. Returns: Pointer to an internal unsigned char[8] array. Do not free or store this pointer across frames; its contents are updated in-place by GHandleWindowEvents. 
unsigned char* keys = GQueryKeyboard();
for (int i = 0; i < 8; i++) {
    if (keys[i] != 0)
        printf("Key held: %d\n", keys[i]);
}
For checking a single specific key, prefer GQueryKeyDown over iterating the array manually.

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GQueryKeyDown

int GQueryKeyDown(int ch)
Returns whether a specific key is currently held down. Scans the internal 8-slot pressed-keys array for a match.
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ch
int
required
The character code to check. Accepts ASCII values (e.g. 'a', ' ') or LWXGL key constants:
ConstantValueKey
LWXGL_KEY_LEFT170Left arrow
LWXGL_KEY_RIGHT171Right arrow
LWXGL_KEY_UP172Up arrow
LWXGL_KEY_DOWN173Down arrow
LWXGL_KEY_FN + n150+nF1–F12
Returns: 1 if the key is currently held, 0 otherwise.

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Frame-loop example

The polling functions work naturally alongside GSimpleWindowLoop. Use GQueryKeyDown inside the per-frame callback for smooth, held-key movement: 
int player_x = 100;
int player_y = 100;

void on_frame(int tick) {
    int x, y, btn;
    GQueryMouse(&x, &y, &btn);

    if (GQueryKeyDown(LWXGL_KEY_LEFT))  player_x -= 2;
    if (GQueryKeyDown(LWXGL_KEY_RIGHT)) player_x += 2;
    if (GQueryKeyDown(LWXGL_KEY_UP))    player_y -= 2;
    if (GQueryKeyDown(LWXGL_KEY_DOWN))  player_y += 2;
}

int main(void) {
    GCreateWindow(640, 480, "Input Demo", 0);
    GSimpleWindowLoop(60, on_frame);
    GTerminateWindow();
    return 0;
}
Because GHandleWindowEvents is called at the start of each frame by GSimpleWindowLoop, GQueryKeyDown always reflects the latest input state when on_frame runs.

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