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Convert css_len2pt and css_len2px for CSS pixels.

This commit is contained in:
Michael Drake 2019-05-06 20:35:31 +01:00
parent 1736bdcfee
commit e02020198d
1 changed files with 20 additions and 15 deletions
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35
content/handlers/css/utils.c
View File

@ -27,6 +27,8 @@
/** Screen DPI in fixed point units: defaults to 90, which RISC OS uses */
css_fixed nscss_screen_dpi = F_90;
/** Medium screen density for device viewing distance. */
css_fixed nscss_baseline_pixel_density = F_96;
/**
* Map viewport-relative length units to either vh or vw.
@ -100,7 +102,7 @@ css_fixed nscss_len2pt(
switch (unit) {
/* We assume the screen and any other output has the same dpi */
/* 1in = DPIpx => 1px = (72/DPI)pt */
case CSS_UNIT_PX: return FDIV(FMUL(length, F_72), nscss_screen_dpi);
case CSS_UNIT_PX: return FDIV(FMUL(length, F_72), F_96);
/* 1in = 72pt */
case CSS_UNIT_IN: return FMUL(length, F_72);
/* 1in = 2.54cm => 1cm = (72/2.54)pt */
@ -115,10 +117,8 @@ css_fixed nscss_len2pt(
case CSS_UNIT_PT: return length;
/* 1pc = 12pt */
case CSS_UNIT_PC: return FMUL(length, INTTOFIX(12));
case CSS_UNIT_VH: return FDIV(FMUL(FDIV((length * ctx->vh), F_100),
F_72), nscss_screen_dpi);
case CSS_UNIT_VW: return FDIV(FMUL(FDIV((length * ctx->vw), F_100),
F_72), nscss_screen_dpi);
case CSS_UNIT_VH: return FDIV(FMUL(FDIV((length * ctx->vh), F_100), F_72), F_96);
case CSS_UNIT_VW: return FDIV(FMUL(FDIV((length * ctx->vw), F_100), F_72), F_96);
default: break;
}
@ -161,7 +161,7 @@ css_fixed nscss_len2px(
/* Convert to pixels (manually, to maximise precision)
* 1in = 72pt => 1pt = (DPI/72)px */
px_per_unit = FDIV(FMUL(font_size, nscss_screen_dpi), F_72);
px_per_unit = FDIV(FMUL(font_size, F_96), F_72);
/* Scale non-em units to em. We have fixed ratios. */
switch (unit) {
@ -190,23 +190,23 @@ css_fixed nscss_len2px(
break;
/* 1in = 2.54cm => 1cm = (DPI/2.54)px */
case CSS_UNIT_CM:
px_per_unit = FDIV(nscss_screen_dpi, FLTTOFIX(2.54));
px_per_unit = FDIV(F_96, FLTTOFIX(2.54));
break;
/* 1in = 25.4mm => 1mm = (DPI/25.4)px */
case CSS_UNIT_MM:
px_per_unit = FDIV(nscss_screen_dpi, FLTTOFIX(25.4));
px_per_unit = FDIV(F_96, FLTTOFIX(25.4));
break;
/* 1in = 101.6q => 1q = (DPI/101.6)px */
case CSS_UNIT_Q:
px_per_unit = FDIV(nscss_screen_dpi, FLTTOFIX(101.6));
px_per_unit = FDIV(F_96, FLTTOFIX(101.6));
break;
/* 1in = 72pt => 1pt = (DPI/72)px */
case CSS_UNIT_PT:
px_per_unit = FDIV(nscss_screen_dpi, F_72);
px_per_unit = FDIV(F_96, F_72);
break;
/* 1pc = 12pt => 1in = 6pc => 1pc = (DPI/6)px */
case CSS_UNIT_PC:
px_per_unit = FDIV(nscss_screen_dpi, INTTOFIX(6));
px_per_unit = FDIV(F_96, INTTOFIX(6));
break;
case CSS_UNIT_REM:
{
@ -228,24 +228,29 @@ css_fixed nscss_len2px(
/* Convert to pixels (manually, to maximise precision)
* 1in = 72pt => 1pt = (DPI/72)px */
px_per_unit = FDIV(FMUL(font_size, nscss_screen_dpi), F_72);
px_per_unit = FDIV(FMUL(font_size, F_96), F_72);
break;
}
/* 1rlh = <user_font_size>pt => 1rlh = (DPI/user_font_size)px */
case CSS_UNIT_RLH:
px_per_unit = FDIV(nscss_screen_dpi, FDIV(
px_per_unit = FDIV(F_96, FDIV(
INTTOFIX(nsoption_int(font_size)),
INTTOFIX(10)));
break;
case CSS_UNIT_VH:
return TRUNCATEFIX((FDIV((length * ctx->vh), F_100) + F_0_5));
px_per_unit = FDIV(ctx->vh, F_100);
break;
case CSS_UNIT_VW:
return TRUNCATEFIX((FDIV((length * ctx->vw), F_100) + F_0_5));
px_per_unit = FDIV(ctx->vw, F_100);
break;
default:
px_per_unit = 0;
break;
}
px_per_unit = FDIV(FMUL(px_per_unit, nscss_screen_dpi),
nscss_baseline_pixel_density);
/* Ensure we round px_per_unit to the nearest whole number of pixels:
* the use of FIXTOINT() below will truncate. */
px_per_unit += F_0_5;