[Android] Build libdjvu

[Frenzie]

References koreader/koreader#1534

[Frenzie]

This one's been bugging me a lot on Android, but I was hoping @marmistrz would tackle it.

There don't seem to be any issues. Here's a screenshot on Android with the following test file: https://en.wikisource.org/wiki/File:Test_rs20846.djvu

[Frenzie]

I was trying to grab a DjVu for testing from the Archive.org website as I'm used to and apparently they quit making new ones?!

https://archive.org/post/1053214/djvu-files-for-new-uploads

An atrocious decision.

Btw @poire-z I didn't look into it but this isn't color-enabled yet. A quick glance suggests this might be the place to look:

koreader-base/djvu.c

Lines 600 to 607 in f0cad8f

	static int drawPage(lua_State *L) {
	DjvuPage *page = (DjvuPage*) luaL_checkudata(L, 1, "djvupage");
	DrawContext *dc = (DrawContext*) lua_topointer(L, 2);
	BlitBuffer *bb = (BlitBuffer*) lua_topointer(L, 3);
	ddjvu_render_mode_t djvu_render_mode = (int) luaL_checkint(L, 6);
	ddjvu_rect_t pagerect, renderrect;
	int bbsize = (bb->w)*(bb->h);
	uint8_t *imagebuffer = bb->data;

[poire-z]

I know. I tried to enable it (and I just tried again), but I can't get something else than this kind of display:

There are other parts to tweak:

koreader-base/djvu.c

Line 101 in f0cad8f

doc->pixelformat = ddjvu_format_create(DDJVU_FORMAT_GREY8, 0, NULL);

koreader-base/djvu.c

Lines 514 to 528 in f0cad8f

	WILLUSBITMAP *dst = &kctx->src;
	bmp_init(dst);
	dst->width = rrect.w;
	dst->height = rrect.h;
	dst->bpp = 8;
	bmp_alloc(dst);
	if (dst->bpp == 8) {
	int ii;
	for (ii = 0; ii < 256; ii++)
	dst->red[ii] = dst->blue[ii] = dst->green[ii] = ii;
	}
	ddjvu_format_set_row_order(page->doc->pixelformat, 1);
	ddjvu_page_render(page->page_ref, 0, &prect, &rrect, page->doc->pixelformat,
	bmp_bytewidth(dst), (char *) dst->data);

with various possibilities:

     doc->pixelformat = ddjvu_format_create(DDJVU_FORMAT_GREY8, 0, NULL);
     doc->pixelformat = ddjvu_format_create(DDJVU_FORMAT_RGB24, 0, NULL);
     static unsigned int masks[4] = {0x00FF0000, 0x0000FF00, 0x000000FF, 0xFF000000};
     doc->pixelformat = ddjvu_format_create(DDJVU_FORMAT_RGBMASK32, 4, masks);

but always that same kind of display.

[Frenzie]

The last one sounds the most interesting to me. I wonder why none of them are working though, weird. (NB Haven't tried it myself.)

[poire-z]

Just for reference, this should make it display correctly the page in colors (with is_color_capable = false commented in djvudocument.lua)

--- a/djvu.c
+++ b/djvu.c
@@ -98,7 +98,9 @@ static int openDocument(lua_State *L) {
        while (! ddjvu_document_decoding_done(doc->doc_ref))
                handle(L, doc->context, True);

-       doc->pixelformat = ddjvu_format_create(DDJVU_FORMAT_GREY8, 0, NULL);
+//     doc->pixelformat = ddjvu_format_create(DDJVU_FORMAT_GREY8, 0, NULL);
+       static unsigned int masks[4] = {0x000000FF, 0x0000FF00, 0x00FF0000, 0xFF000000};
+       doc->pixelformat = ddjvu_format_create(DDJVU_FORMAT_RGBMASK32, 4, masks);
        if (! doc->pixelformat) {
                return luaL_error(L, "cannot create DjVu pixelformat for <%s>", filename);
        }
@@ -603,7 +605,7 @@ static int drawPage(lua_State *L) {
        BlitBuffer *bb = (BlitBuffer*) lua_topointer(L, 3);
        ddjvu_render_mode_t djvu_render_mode = (int) luaL_checkint(L, 6);
        ddjvu_rect_t pagerect, renderrect;
-       int bbsize = (bb->w)*(bb->h);
+       int bbsize = (bb->w)*(bb->h)*4;
        uint8_t *imagebuffer = bb->data;

        /*printf("@page %d, @@zoom:%f, offset: (%d, %d)\n", page->num, dc->zoom, dc->offset_x, dc->offset_y);*/
@@ -638,7 +640,7 @@ static int drawPage(lua_State *L) {
         * So we don't set rotation here.
         */

-       if (!ddjvu_page_render(page->page_ref, djvu_render_mode, &pagerect, &renderrect, page->doc->pixelformat, bb->w, imagebuffer))
+       if (!ddjvu_page_render(page->page_ref, djvu_render_mode, &pagerect, &renderrect, page->doc->pixelformat, bb->w*4, imagebuffer))
                memset(imagebuffer, 0xFF, bbsize);

        /* Gamma correction of the blitbuffer, do we need to build this into BlitBuffer? */

But it then crashes when you change zoom mode to Fit content (which it seems wants some RGB24, but even when you give it RGB24, it truncates the page in its 1/3...)
edit: should be OK with RGB24 and two ->bpp = 8 to change to 24.

[Frenzie]

Minor update, upstream has now incorporated this: https://gitlab.com/koreader/djvulibre/-/commit/8e79901a927d7b20b629f5240e64f617d67f3dff