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Round down any canvas-relative mouse event coordinates (fixes SAFE_HEAP asserts) #21429

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Merged
sbc100 merged 2 commits into from
Feb 26, 2024
Merged

Round down any canvas-relative mouse event coordinates (fixes SAFE_HEAP asserts) #21429

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f439403
Round down any canvas-relative mouse coordinates
cwoffenden Feb 26, 2024
7c40ca4
Improved docs wording
cwoffenden Feb 26, 2024
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4 changes: 2 additions & 2 deletions site/source/docs/api_reference/html5.h.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -419,13 +419,13 @@ Struct
.. c:member:: long targetX
long targetY

These fields give the mouse coordinates mapped relative to the coordinate space of the target DOM element receiving the input events (Emscripten-specific extension).
These fields give the mouse coordinates mapped relative to the coordinate space of the target DOM element receiving the input events (Emscripten-specific extension; coordinates are rounded down to the nearest integer).


.. c:member:: long canvasX
long canvasY

These fields give the mouse coordinates mapped to the Emscripten canvas client area (Emscripten-specific extension).
These fields give the mouse coordinates mapped to the Emscripten canvas client area (Emscripten-specific extension; coordinates are rounded down the nearest integer).


.. c:member:: long padding
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17 changes: 9 additions & 8 deletions src/library_html5.js
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Expand Up @@ -481,16 +481,17 @@ var LibraryHTML5 = {
#if !DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR
if (Module['canvas']) {
var rect = getBoundingClientRect(Module['canvas']);
HEAP32[idx + {{{ C_STRUCTS.EmscriptenMouseEvent.canvasX / 4 }}}] = e.clientX - rect.left;
HEAP32[idx + {{{ C_STRUCTS.EmscriptenMouseEvent.canvasY / 4 }}}] = e.clientY - rect.top;
HEAP32[idx + {{{ C_STRUCTS.EmscriptenMouseEvent.canvasX / 4 }}}] = e.clientX - (rect.left | 0);
HEAP32[idx + {{{ C_STRUCTS.EmscriptenMouseEvent.canvasY / 4 }}}] = e.clientY - (rect.top | 0);
} else { // Canvas is not initialized, return 0.
HEAP32[idx + {{{ C_STRUCTS.EmscriptenMouseEvent.canvasX / 4 }}}] = 0;
HEAP32[idx + {{{ C_STRUCTS.EmscriptenMouseEvent.canvasY / 4 }}}] = 0;
}
#endif
// Note: rect contains doubles (truncated to placate SAFE_HEAP, which is the same behaviour when writing to HEAP32 anyway)
var rect = getBoundingClientRect(target);
HEAP32[idx + {{{ C_STRUCTS.EmscriptenMouseEvent.targetX / 4 }}}] = e.clientX - rect.left;
HEAP32[idx + {{{ C_STRUCTS.EmscriptenMouseEvent.targetY / 4 }}}] = e.clientY - rect.top;
HEAP32[idx + {{{ C_STRUCTS.EmscriptenMouseEvent.targetX / 4 }}}] = e.clientX - (rect.left | 0);
HEAP32[idx + {{{ C_STRUCTS.EmscriptenMouseEvent.targetY / 4 }}}] = e.clientY - (rect.top | 0);

#if MIN_SAFARI_VERSION <= 80000 || MIN_CHROME_VERSION <= 21 // https://caniuse.com/#search=movementX
#if MIN_CHROME_VERSION <= 76
Expand Down Expand Up @@ -1945,11 +1946,11 @@ var LibraryHTML5 = {
HEAP32[idx + {{{ C_STRUCTS.EmscriptenTouchPoint.pageY / 4}}}] = t.pageY;
HEAP32[idx + {{{ C_STRUCTS.EmscriptenTouchPoint.isChanged / 4}}}] = t.isChanged;
HEAP32[idx + {{{ C_STRUCTS.EmscriptenTouchPoint.onTarget / 4}}}] = t.onTarget;
HEAP32[idx + {{{ C_STRUCTS.EmscriptenTouchPoint.targetX / 4}}}] = t.clientX - targetRect.left;
HEAP32[idx + {{{ C_STRUCTS.EmscriptenTouchPoint.targetY / 4}}}] = t.clientY - targetRect.top;
HEAP32[idx + {{{ C_STRUCTS.EmscriptenTouchPoint.targetX / 4}}}] = t.clientX - (targetRect.left | 0);
HEAP32[idx + {{{ C_STRUCTS.EmscriptenTouchPoint.targetY / 4}}}] = t.clientY - (targetRect.top | 0);
#if !DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR
HEAP32[idx + {{{ C_STRUCTS.EmscriptenTouchPoint.canvasX / 4}}}] = canvasRect ? t.clientX - canvasRect.left : 0;
HEAP32[idx + {{{ C_STRUCTS.EmscriptenTouchPoint.canvasY / 4}}}] = canvasRect ? t.clientY - canvasRect.top : 0;
HEAP32[idx + {{{ C_STRUCTS.EmscriptenTouchPoint.canvasX / 4}}}] = canvasRect ? t.clientX - (canvasRect.left | 0) : 0;
HEAP32[idx + {{{ C_STRUCTS.EmscriptenTouchPoint.canvasY / 4}}}] = canvasRect ? t.clientY - (canvasRect.top | 0) : 0;
#endif

idx += {{{ C_STRUCTS.EmscriptenTouchPoint.__size__ / 4 }}};
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