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#7992 Isolate PDF SMask #2361

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Merged
Frenzie merged 16 commits into from
May 18, 2026
Merged

#7992 Isolate PDF SMask #2361

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7771c4e
draft of custom device
kerivin May 17, 2026
d6ed7b6
minor improvements
kerivin May 17, 2026
d667ff0
fallback to normal drawing if no smask
kerivin May 17, 2026
cf20a43
minor improvements
kerivin May 17, 2026
763abc3
minor improvement
kerivin May 17, 2026
2c549c1
init isolate_smask in DrawContext
kerivin May 17, 2026
c41585c
minor improvements
kerivin May 17, 2026
4357095
forgotten arg in constructor
kerivin May 17, 2026
3d564a4
extra whitespace removed
kerivin May 17, 2026
bce60ed
persistent smask bug fixed
kerivin May 17, 2026
10fae40
new line
kerivin May 17, 2026
10ea222
one line instead of two
kerivin May 17, 2026
b6dbb58
new_line
kerivin May 17, 2026
8f9bcef
moved fz_new_isolated_smask_device to wrap-mupdf.c
kerivin May 17, 2026
a8a938f
Update ffi/mupdf.lua
Frenzie May 18, 2026
e165612
Apply suggestion from @Frenzie
Frenzie May 18, 2026
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1 change: 1 addition & 0 deletions drawcontext.h
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,7 @@ typedef struct DrawContext {
double gamma;
int offset_x;
int offset_y;
int isolate_smask;
} DrawContext;

#endif
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1 change: 1 addition & 0 deletions ffi-cdecl/wrap-mupdf_cdecl.c
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Original file line number Diff line number Diff line change
Expand Up @@ -136,6 +136,7 @@ cdecl_func(fz_device_bgr)
/* device, rendering */
cdecl_func(mupdf_new_draw_device)
cdecl_func(mupdf_new_bbox_device)
cdecl_func(mupdf_new_isolated_smask_device)
cdecl_func(mupdf_run_page)
cdecl_func(fz_close_device)
cdecl_func(fz_drop_device)
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7 changes: 5 additions & 2 deletions ffi/drawcontext.lua
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,7 @@ typedef struct DrawContext {
double gamma;
int offset_x;
int offset_y;
int isolate_smask;
} DrawContext;
]]

Expand All @@ -30,11 +31,13 @@ end
function DC_mt.__index:getOffset() return self.offset_x, self.offset_y end
function DC_mt.__index:setGamma(gamma) self.gamma = gamma end
function DC_mt.__index:getGamma() return self.gamma end
function DC_mt.__index:setIsolateSMask(isolate_smask) self.isolate_smask = isolate_smask end
function DC_mt.__index:getIsolateSMask() return self.isolate_smask end

local dctype = ffi.metatype("DrawContext", DC_mt)

function DC.new(rotate, zoom, x, y, gamma)
return dctype(rotate or 0, zoom or 1.0, gamma or -1.0, x or 0, y or 0)
function DC.new(rotate, zoom, x, y, gamma, isolate_smask)
return dctype(rotate or 0, zoom or 1.0, gamma or -1.0, x or 0, y or 0, isolate_smask or 0)
end

return DC
21 changes: 17 additions & 4 deletions ffi/mupdf.lua
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Original file line number Diff line number Diff line change
Expand Up @@ -670,15 +670,28 @@ function page_mt.__index:getPageLinks()
return links
end

local function run_page(page, pixmap, ctm)
local function run_page(page, pixmap, ctm, isolate_smask)
M.fz_clear_pixmap_with_value(page.ctx, pixmap, 0xff)

local dev = W.mupdf_new_draw_device(page.ctx, nil, pixmap)
if dev == nil then merror(page.ctx, "cannot create draw device") end

local ok = W.mupdf_run_page(page.ctx, page.page, dev, ctm, nil)
local ok = false
if isolate_smask then
local smask_dev = W.mupdf_new_isolated_smask_device(page.ctx, dev)
if smask_dev then
ok = W.mupdf_run_page(page.ctx, page.page, smask_dev, ctm, nil)
M.fz_close_device(page.ctx, smask_dev)
M.fz_drop_device(page.ctx, smask_dev)
end
end
if not ok then
ok = W.mupdf_run_page(page.ctx, page.page, dev, ctm, nil)
end

M.fz_close_device(page.ctx, dev)
M.fz_drop_device(page.ctx, dev)

if ok == nil then merror(page.ctx, "could not run page") end
end
--[[
Expand Down Expand Up @@ -717,7 +730,7 @@ function page_mt.__index:draw_new(draw_context, width, height, offset_x, offset_
self.ctx, colorspace, bbox, nil, self.doc.color and 1 or 0, ffi.cast("unsigned char*", bb.data))
if pix == nil then merror(self.ctx, "cannot allocate pixmap") end

run_page(self, pix, ctm)
run_page(self, pix, ctm, draw_context.isolate_smask == 1)

if draw_context.gamma >= 0.0 then
M.fz_gamma_pixmap(self.ctx, pix, draw_context.gamma)
Expand Down Expand Up @@ -1087,7 +1100,7 @@ local function render_for_kopt(bmp, page, scale, bounds)
local pix = W.mupdf_new_pixmap_with_bbox(page.ctx, colorspace, bbox, nil, 1)
if pix == nil then merror(page.ctx, "could not allocate pixmap") end

run_page(page, pix, ctm)
run_page(page, pix, ctm, false)

k2pdfopt.bmp_init(bmp)

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1 change: 1 addition & 0 deletions ffi/mupdf_h.lua
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Original file line number Diff line number Diff line change
Expand Up @@ -248,6 +248,7 @@ fz_colorspace *fz_device_rgb(fz_context *);
fz_colorspace *fz_device_bgr(fz_context *);
fz_device *mupdf_new_draw_device(fz_context *, const fz_matrix *, fz_pixmap *);
fz_device *mupdf_new_bbox_device(fz_context *, fz_rect *);
fz_device *mupdf_new_isolated_smask_device(fz_context *, fz_device *);
void *mupdf_run_page(fz_context *, fz_page *, fz_device *, const fz_matrix *, fz_cookie *);
void fz_close_device(fz_context *, fz_device *);
void fz_drop_device(fz_context *, fz_device *);
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23 changes: 23 additions & 0 deletions wrap-mupdf.c
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Original file line number Diff line number Diff line change
Expand Up @@ -203,6 +203,29 @@ fz_rect *mupdf_fz_bound_page(fz_context *ctx, fz_page *page, fz_rect *r) {
return r;
}

typedef struct
{
fz_device super;
fz_device* default_device;
} isolated_smask_device;

static void smask_fill_image(fz_context* ctx, fz_device* dev, fz_image* img, fz_matrix ctm, float alpha, fz_color_params color_params)
{
if (img->mask) {
isolated_smask_device* smask_dev = (isolated_smask_device*)dev;
float black[1] = { 0.f };
fz_fill_image_mask(ctx, smask_dev->default_device, img->mask, ctm, fz_device_gray(ctx), black, alpha, color_params);

@Frenzie Frenzie May 18, 2026

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Is it correct that fz_device_gray doesn't need any cleanup?

@kerivin kerivin May 18, 2026 •
edited
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Seems like it.
Here's an example from the official documentation:

float cmyk[100][4] = { {1,0,0,0}, ...
float rgb[100][3];
fz_color_converter cc;
int i;

fz_find_color_converter(ctx,
	&cc,
	fz_device_cmyk(ctx),
	fz_device_rgb(ctx),
	NULL,
	fz_default_color_params(ctx)
);
for (i = 0; i < 100; ++i)
	cc.convert(ctx, &cc, cmyk[i], rgb[i]);
fz_drop_color_converter(ctx, &cc);

@benoit-pierre benoit-pierre May 18, 2026

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/**
	Retrieve global default colorspaces.

	These return borrowed references that should not be dropped,
	unless they are kept first.
*/
fz_colorspace *fz_device_gray(fz_context *ctx);
fz_colorspace *fz_device_rgb(fz_context *ctx);
fz_colorspace *fz_device_bgr(fz_context *ctx);
fz_colorspace *fz_device_cmyk(fz_context *ctx);
fz_colorspace *fz_device_lab(fz_context *ctx);

}
}

fz_device *fz_new_isolated_smask_device(fz_context* ctx, fz_device* dev)
{
isolated_smask_device* smask_dev = fz_new_derived_device(ctx, isolated_smask_device);
smask_dev->default_device = dev;
smask_dev->super.fill_image = smask_fill_image;
return (fz_device*)smask_dev;
}

/* wrappers for functions that throw exceptions mupdf-style (setjmp/longjmp) */

#define MUPDF_DO_WRAP
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3 changes: 3 additions & 0 deletions wrap-mupdf.h
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Original file line number Diff line number Diff line change
Expand Up @@ -114,6 +114,9 @@ MUPDF_WRAP(mupdf_new_bbox_device, fz_device*, NULL,
MUPDF_WRAP(mupdf_new_draw_device, fz_device*, NULL,
ret = fz_new_draw_device(ctx, transform ? *transform : fz_identity, dest),
const fz_matrix *transform, fz_pixmap *dest)
MUPDF_WRAP(mupdf_new_isolated_smask_device, fz_device*, NULL,
ret = fz_new_isolated_smask_device(ctx, dev),
fz_device *dev)
MUPDF_WRAP(mupdf_run_page, void*, NULL,
{ fz_run_page(ctx, page, dev, *transform, cookie); ret = (void*) -1; },
fz_page *page, fz_device *dev, const fz_matrix *transform, fz_cookie *cookie)
Expand Down