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LibWeb: Remove implicit conversion from float and double to CSSPixels

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In general it is not safe to convert any arbitrary floating-point value
to CSSPixels. CSSPixels has a resolution of 0.015625, which for small
values (e.g. scale factors between 0 and 1), can produce bad results
if converted to CSSPixels then scaled back up. In the worst case values
can underflow to zero and produce incorrect results.
This commit is contained in:
MacDue 2023-08-26 15:03:04 +01:00 • committed by Alexander Kalenik
parent 0f9c088302
commit 360c0eb509
43 changed files with 248 additions and 221 deletions
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12
Userland/Libraries/LibWeb/Layout/Node.cpp
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@ -300,11 +300,11 @@ static CSSPixels snap_a_length_as_a_border_width(double device_pixels_per_css_pi
// 3. If len is greater than zero, but less than 1 device pixel, round len up to 1 device pixel.
if (device_pixels > 0 && device_pixels < 1)
return 1 / device_pixels_per_css_pixel;
return CSSPixels(1 / device_pixels_per_css_pixel);
// 4. If len is greater than 1 device pixel, round it down to the nearest integer number of device pixels.
if (device_pixels > 1)
return floor(device_pixels) / device_pixels_per_css_pixel;
return CSSPixels(floor(device_pixels) / device_pixels_per_css_pixel);
return length;
}
@ -684,11 +684,11 @@ void NodeWithStyle::apply_style(const CSS::StyleProperties& computed_style)
// https://www.w3.org/TR/css-backgrounds-3/#valdef-line-width-thin
switch (value->to_identifier()) {
case CSS::ValueID::Thin:
return 1.0;
return 1;
case CSS::ValueID::Medium:
return 3.0;
return 3;
case CSS::ValueID::Thick:
return 5.0;
return 5;
default:
VERIFY_NOT_REACHED();
}
@ -742,7 +742,7 @@ void NodeWithStyle::apply_style(const CSS::StyleProperties& computed_style)
// FIXME: Converting to pixels isn't really correct - values should be in "user units"
// https://svgwg.org/svg2-draft/coords.html#TermUserUnits
if (stroke_width->is_number())
computed_values.set_stroke_width(CSS::Length::make_px(stroke_width->as_number().number()));
computed_values.set_stroke_width(CSS::Length::make_px(CSSPixels(stroke_width->as_number().number())));
else if (stroke_width->is_length())
computed_values.set_stroke_width(stroke_width->as_length().length());
else if (stroke_width->is_percentage())