feat(font): add option to disable kerning (#4725)

2023-10-30 13:23:20 +01:00
parent d197d73d62
commit 8fabcc6853
9 changed files with 177 additions and 8 deletions
--- a/docs/overview/font.rst
+++ b/docs/overview/font.rst
@@ -208,6 +208,20 @@ because
 - they can be compressed better
 - and probably they are used less frequently then the medium-sized fonts, so the performance cost is smaller.

+Kerning
+-------
+
+Fonts may provide kerning information to adjust the spacing between specific
+characters.
+
+- The online converter generates kerning tables.
+- The offline converter generates kerning tables unless ``--no-kerning`` is
+  specified.
+- FreeType integration does not currently support kerning.
+- The Tiny TTF font engine supports GPOS and Kern tables.
+
+To configure kerning at runtime, use :cpp:func:`lv_font_set_kerning`.
+
 .. _add_font:

 Add a new font
--- a/src/font/lv_font.c
+++ b/src/font/lv_font.c
@@ -62,7 +62,7 @@ bool lv_font_get_glyph_dsc(const lv_font_t * font_p, lv_font_glyph_dsc_t * dsc_o
    dsc_out->resolved_font = NULL;

    while(f) {
-        bool found = f->get_glyph_dsc(f, dsc_out, letter, letter_next);
+        bool found = f->get_glyph_dsc(f, dsc_out, letter, f->kerning == LV_FONT_KERNING_NONE ? 0 : letter_next);
        if(found) {
            if(!dsc_out->is_placeholder) {
                dsc_out->resolved_font = f;
@@ -79,7 +79,8 @@ bool lv_font_get_glyph_dsc(const lv_font_t * font_p, lv_font_glyph_dsc_t * dsc_o

 #if LV_USE_FONT_PLACEHOLDER
    if(placeholder_font != NULL) {
-        placeholder_font->get_glyph_dsc(placeholder_font, dsc_out, letter, letter_next);
+        placeholder_font->get_glyph_dsc(placeholder_font, dsc_out, letter,
+                                        placeholder_font->kerning == LV_FONT_KERNING_NONE ? 0 : letter_next);
        dsc_out->resolved_font = placeholder_font;
        return true;
    }
@@ -119,6 +120,12 @@ uint16_t lv_font_get_glyph_width(const lv_font_t * font, uint32_t letter, uint32
    return g.adv_w;
 }

+void lv_font_set_kerning(lv_font_t * font, lv_font_kerning_t kerning)
+{
+    LV_ASSERT_NULL(font);
+    font->kerning = kerning;
+}
+
 /**********************
 *   STATIC FUNCTIONS
 **********************/
--- a/src/font/lv_font.h
+++ b/src/font/lv_font.h
@@ -64,6 +64,18 @@ typedef _lv_font_subpx_t lv_font_subpx_t;
 typedef uint8_t lv_font_subpx_t;
 #endif /*DOXYGEN*/

+/** Adjust letter spacing for specific character pairs.*/
+enum _lv_font_kerning_t {
+    LV_FONT_KERNING_NORMAL,
+    LV_FONT_KERNING_NONE,
+};
+
+#ifdef DOXYGEN
+typedef _lv_font_kerning_t lv_font_kerning_t;
+#else
+typedef uint8_t lv_font_kerning_t;
+#endif /*DOXYGEN*/
+
 /** Describe the properties of a font*/
 typedef struct _lv_font_t {
    /** Get a glyph's descriptor from a font*/
@@ -76,6 +88,7 @@ typedef struct _lv_font_t {
    lv_coord_t line_height;         /**< The real line height where any text fits*/
    lv_coord_t base_line;           /**< Base line measured from the top of the line_height*/
    uint8_t subpx   : 2;            /**< An element of `lv_font_subpx_t`*/
+    uint8_t kerning : 1;            /**< An element of `lv_font_kerning_t`*/

    int8_t underline_position;      /**< Distance between the top of the underline and base line (< 0 means below the base line)*/
    int8_t underline_thickness;     /**< Thickness of the underline*/
@@ -128,6 +141,13 @@ static inline lv_coord_t lv_font_get_line_height(const lv_font_t * font)
    return font->line_height;
 }

+/**
+ * Configure the use of kerning information stored in a font
+ * @param font    pointer to a font
+ * @param kerning `LV_FONT_KERNING_NORMAL` (default) or `LV_FONT_KERNING_NONE`
+ */
+void lv_font_set_kerning(lv_font_t * font, lv_font_kerning_t kerning);
+
 /**********************
 *      MACROS
 **********************/
--- a/src/font/lv_font_loader.c
+++ b/src/font/lv_font_loader.c
@@ -572,6 +572,7 @@ static bool lvgl_load_font(lv_fs_file_t * fp, lv_font_t * font)
        return false;
    }

+    /*kerning*/
    if(font_header.tables_count < 4) {
        font_dsc->kern_dsc = NULL;
        font_dsc->kern_classes = 0;
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -162,6 +162,7 @@ add_library(test_common
        src/test_assets/test_img_lvgl_logo_png.c
        src/test_assets/test_img_lvgl_logo_jpg.c
        src/test_assets/ubuntu_font.c
+        src/test_assets/kern_one_otf.c
        unity/unity_support.c
        unity/unity.c
 )
--- a/tests/ref_imgs/tiny_ttf_2.png
+++ b/tests/ref_imgs/tiny_ttf_2.png
--- a/tests/src/test_assets/kern_one_otf.c
+++ b/tests/src/test_assets/kern_one_otf.c
@@ -0,0 +1,95 @@
+#include <stdint.h>
+#include <stddef.h>
+
+/*TestKERNOne.otf from https://github.com/unicode-org/text-rendering-tests*/
+const uint8_t kern_one_otf[] = {
+  0x4f, 0x54, 0x54, 0x4f, 0x00, 0x0a, 0x00, 0x80, 0x00, 0x03, 0x00, 0x20, 0x43, 0x46, 0x46, 0x20,
+  0x20, 0xda, 0x90, 0x5b, 0x00, 0x00, 0x03, 0xb8, 0x00, 0x00, 0x01, 0x66, 0x4f, 0x53, 0x2f, 0x32,
+  0x5a, 0x11, 0x87, 0xea, 0x00, 0x00, 0x01, 0x10, 0x00, 0x00, 0x00, 0x60, 0x63, 0x6d, 0x61, 0x70,
+  0x02, 0x92, 0x00, 0x18, 0x00, 0x00, 0x03, 0x4c, 0x00, 0x00, 0x00, 0x4c, 0x68, 0x65, 0x61, 0x64,
+  0x0d, 0xf9, 0x3b, 0x43, 0x00, 0x00, 0x00, 0xac, 0x00, 0x00, 0x00, 0x36, 0x68, 0x68, 0x65, 0x61,
+  0x06, 0x42, 0x01, 0xc8, 0x00, 0x00, 0x00, 0xe4, 0x00, 0x00, 0x00, 0x24, 0x68, 0x6d, 0x74, 0x78,
+  0x08, 0xfc, 0x00, 0xf3, 0x00, 0x00, 0x05, 0x20, 0x00, 0x00, 0x00, 0x14, 0x6b, 0x65, 0x72, 0x6e,
+  0x01, 0x54, 0xfd, 0xe7, 0x00, 0x00, 0x05, 0x34, 0x00, 0x00, 0x00, 0x30, 0x6d, 0x61, 0x78, 0x70,
+  0x00, 0x05, 0x50, 0x00, 0x00, 0x00, 0x01, 0x08, 0x00, 0x00, 0x00, 0x06, 0x6e, 0x61, 0x6d, 0x65,
+  0xe2, 0x60, 0xf2, 0x44, 0x00, 0x00, 0x01, 0x70, 0x00, 0x00, 0x01, 0xda, 0x70, 0x6f, 0x73, 0x74,
+  0xff, 0xb8, 0x00, 0x32, 0x00, 0x00, 0x03, 0x98, 0x00, 0x00, 0x00, 0x20, 0x00, 0x01, 0x00, 0x00,
+  0x00, 0x01, 0x00, 0x00, 0x7f, 0x24, 0x30, 0xed, 0x5f, 0x0f, 0x3c, 0xf5, 0x00, 0x03, 0x03, 0xe8,
+  0x00, 0x00, 0x00, 0x00, 0xd3, 0xef, 0x1e, 0xed, 0x00, 0x00, 0x00, 0x00, 0xd8, 0x9a, 0xd9, 0x1e,
+  0x00, 0x32, 0xff, 0x38, 0x02, 0x26, 0x03, 0x20, 0x00, 0x00, 0x00, 0x03, 0x00, 0x02, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x03, 0xe8, 0xff, 0x38, 0x00, 0x00, 0x02, 0x58,
+  0x00, 0x32, 0x00, 0x32, 0x02, 0x26, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x05, 0x00, 0x00, 0x50, 0x00, 0x00, 0x05, 0x00, 0x00,
+  0x00, 0x03, 0x01, 0xcc, 0x01, 0x90, 0x00, 0x05, 0x00, 0x08, 0x02, 0x8a, 0x02, 0x58, 0x00, 0x00,
+  0x00, 0x4b, 0x02, 0x8a, 0x02, 0x58, 0x00, 0x00, 0x01, 0x5e, 0x00, 0x32, 0x01, 0x2c, 0x00, 0x00,
+  0x00, 0x00, 0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x55, 0x4e, 0x49, 0x43, 0x00, 0x40,
+  0x00, 0x20, 0x01, 0x31, 0x03, 0x20, 0xff, 0x38, 0x00, 0xc8, 0x03, 0xe8, 0x00, 0xc8, 0x20, 0x00,
+  0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x01, 0xf4, 0x02, 0xbc, 0x00, 0x00, 0x00, 0x20, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x0c, 0x00, 0x96, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1e,
+  0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x15, 0x00, 0x1e, 0x00, 0x01,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0x07, 0x00, 0x33, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x06, 0x00, 0x1b, 0x00, 0x3a, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x09, 0x00, 0x0d,
+  0x00, 0x55, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x13, 0x00, 0x0a, 0x00, 0x62, 0x00, 0x03,
+  0x00, 0x01, 0x04, 0x09, 0x00, 0x00, 0x00, 0x3c, 0x00, 0x6c, 0x00, 0x03, 0x00, 0x01, 0x04, 0x09,
+  0x00, 0x01, 0x00, 0x2a, 0x00, 0xa8, 0x00, 0x03, 0x00, 0x01, 0x04, 0x09, 0x00, 0x02, 0x00, 0x0e,
+  0x00, 0xd2, 0x00, 0x03, 0x00, 0x01, 0x04, 0x09, 0x00, 0x06, 0x00, 0x36, 0x00, 0xe0, 0x00, 0x03,
+  0x00, 0x01, 0x04, 0x09, 0x00, 0x09, 0x00, 0x1a, 0x01, 0x16, 0x00, 0x03, 0x00, 0x01, 0x04, 0x09,
+  0x00, 0x13, 0x00, 0x14, 0x01, 0x30, 0x43, 0x6f, 0x70, 0x79, 0x72, 0x69, 0x67, 0x68, 0x74, 0x20,
+  0xa9, 0x20, 0x32, 0x30, 0x31, 0x36, 0x20, 0x55, 0x6e, 0x69, 0x63, 0x6f, 0x64, 0x65, 0x2c, 0x20,
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+  0x01, 0x31, 0xff, 0xff, 0xff, 0xe4, 0xff, 0xad, 0xff, 0x8e, 0xfe, 0xd1, 0x00, 0x01, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0xff, 0xb5, 0x00, 0x32, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x04, 0x04, 0x00, 0x01, 0x01, 0x01,
+  0x1c, 0x4f, 0x70, 0x65, 0x6e, 0x54, 0x79, 0x70, 0x65, 0x54, 0x65, 0x73, 0x74, 0x4b, 0x45, 0x52,
+  0x4e, 0x4f, 0x6e, 0x65, 0x2d, 0x52, 0x65, 0x67, 0x75, 0x6c, 0x61, 0x72, 0x00, 0x01, 0x01, 0x01,
+  0x1f, 0xf8, 0x0f, 0x00, 0xf8, 0x1b, 0x01, 0xf8, 0x1c, 0x02, 0xf8, 0x18, 0x04, 0xbd, 0xfb, 0x5c,
+  0xf8, 0xba, 0xf9, 0xb4, 0x05, 0xf7, 0x22, 0x0f, 0x94, 0xf7, 0xf1, 0x12, 0xf7, 0x2b, 0x11, 0x00,
+  0x02, 0x01, 0x01, 0x21, 0x3e, 0x43, 0x6f, 0x70, 0x79, 0x72, 0x69, 0x67, 0x68, 0x74, 0x20, 0x28,
+  0x43, 0x29, 0x20, 0x32, 0x30, 0x31, 0x36, 0x20, 0x55, 0x6e, 0x69, 0x63, 0x6f, 0x64, 0x65, 0x2c,
+  0x20, 0x49, 0x6e, 0x63, 0x2e, 0x4f, 0x70, 0x65, 0x6e, 0x54, 0x79, 0x70, 0x65, 0x54, 0x65, 0x73,
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+  0x05, 0x01, 0x01, 0x89, 0xa0, 0xaa, 0xbb, 0xbe, 0xf8, 0x88, 0xf8, 0x2e, 0xf9, 0xb4, 0x15, 0xfb,
+  0xd1, 0xfe, 0x7c, 0xf7, 0xd1, 0x06, 0x3e, 0xf7, 0xd2, 0x15, 0xfb, 0x05, 0xfb, 0x3a, 0xf7, 0x05,
+  0x07, 0xf7, 0x19, 0x6a, 0x15, 0x27, 0x5c, 0xef, 0x06, 0xac, 0xf7, 0x91, 0x15, 0xfb, 0x05, 0xfb,
+  0x3a, 0xf7, 0x05, 0xac, 0x3b, 0xef, 0xba, 0x6a, 0x74, 0x69, 0xc3, 0x07, 0xef, 0xf7, 0x0e, 0x15,
+  0x27, 0xfb, 0x3a, 0xad, 0xf7, 0x19, 0xcd, 0x07, 0xac, 0xc7, 0x15, 0x6a, 0x49, 0x45, 0x27, 0xac,
+  0xcd, 0xb0, 0x49, 0xac, 0x07, 0xcd, 0xec, 0x15, 0x6a, 0x67, 0xac, 0x06, 0xad, 0xd1, 0x15, 0x45,
+  0xcd, 0x69, 0xfb, 0x3a, 0xf3, 0x07, 0xf7, 0x3a, 0xf7, 0x15, 0x15, 0x6a, 0x49, 0x66, 0xcd, 0x6a,
+  0xfb, 0x3a, 0xac, 0xcd, 0xb0, 0x4a, 0xac, 0x07, 0xf7, 0x39, 0xfd, 0x83, 0x15, 0x6a, 0x6b, 0x07,
+  0x45, 0x5c, 0x05, 0xf1, 0x6a, 0xfb, 0x3a, 0xac, 0x06, 0xd1, 0xba, 0x05, 0x45, 0xac, 0x06, 0x0e,
+  0xf8, 0xec, 0xbd, 0xf8, 0x88, 0x15, 0xef, 0xef, 0xef, 0xfc, 0xec, 0xef, 0xf8, 0xec, 0xef, 0x27,
+  0xef, 0xf7, 0x5c, 0xfc, 0x88, 0x06, 0x0e, 0xf7, 0x5c, 0xbd, 0x16, 0xef, 0xf8, 0x88, 0x27, 0x06,
+  0x0e, 0xf8, 0x24, 0xbd, 0x16, 0xf7, 0xc0, 0xf8, 0x88, 0x27, 0xfc, 0x24, 0x27, 0xf8, 0x24, 0x27,
+  0x06, 0x0e, 0xf8, 0xec, 0x0e, 0x1e, 0xa0, 0x37, 0xff, 0x0c, 0x09, 0x8b, 0x0c, 0x0b, 0x00, 0x00,
+  0x01, 0xf4, 0x00, 0x5d, 0x02, 0x58, 0x00, 0x32, 0x00, 0xc8, 0x00, 0x32, 0x01, 0x90, 0x00, 0x32,
+  0x02, 0x58, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x2c, 0x00, 0x01, 0x00, 0x05,
+  0x00, 0x18, 0x00, 0x02, 0x00, 0x06, 0x00, 0x01, 0x00, 0x02, 0xff, 0x38, 0x00, 0x01, 0x00, 0x03,
+  0xff, 0x38, 0x00, 0x02, 0x00, 0x01, 0xff, 0x38, 0x00, 0x02, 0x00, 0x02, 0x01, 0xf4, 0x00, 0x03,
+  0x00, 0x01, 0xff, 0x38
+};
+
+const size_t kern_one_otf_size = sizeof(kern_one_otf);
--- a/tests/src/test_assets/ubuntu_font.c
+++ b/tests/src/test_assets/ubuntu_font.c
@@ -1,6 +1,3 @@
-#ifndef UBUNTU_FONT_H
-#define UBUNTU_FONT_H
-
 #include <stdint.h>
 #include <stddef.h>

@@ -11971,4 +11968,3 @@ const uint8_t ubuntu_font[] = {
 };

 size_t ubuntu_font_size = sizeof(ubuntu_font);
-#endif
--- a/tests/src/test_cases/libs/test_tiny_ttf.c
+++ b/tests/src/test_cases/libs/test_tiny_ttf.c
@@ -29,7 +29,6 @@ void test_tiny_ttf_rendering_test(void)
    lv_style_set_bg_opa(&style, LV_OPA_COVER);
    lv_style_set_bg_color(&style, lv_color_hex(0xffaaaa));

-
    /*Create a label with the new style*/
    lv_obj_t * label = lv_label_create(lv_screen_active());
    lv_obj_add_style(label, &style, 0);
@@ -39,6 +38,42 @@ void test_tiny_ttf_rendering_test(void)
    lv_obj_center(label);

    TEST_ASSERT_EQUAL_SCREENSHOT("tiny_ttf_1.png");
+
+    lv_obj_del(label);
+    lv_tiny_ttf_destroy(font);
+#else
+    TEST_PASS();
+#endif
+}
+
+void test_tiny_ttf_kerning()
+{
+#if LV_USE_TINY_TTF
+    extern const uint8_t kern_one_otf[];
+    extern size_t kern_one_otf_size;
+    lv_font_t * font_normal = lv_tiny_ttf_create_data(kern_one_otf, kern_one_otf_size, 80);
+    lv_font_t * font_none = lv_tiny_ttf_create_data(kern_one_otf, kern_one_otf_size, 80);
+    lv_font_set_kerning(font_none, LV_FONT_KERNING_NONE);
+
+    lv_obj_t * cont = lv_obj_create(lv_screen_active());
+    lv_obj_set_size(cont, lv_pct(90), lv_pct(90));
+    lv_obj_center(cont);
+    lv_obj_set_flex_flow(cont, LV_FLEX_FLOW_ROW);
+    lv_obj_set_flex_align(cont, LV_FLEX_ALIGN_SPACE_EVENLY, LV_FLEX_ALIGN_CENTER, LV_FLEX_ALIGN_CENTER);
+
+    lv_obj_t * label_normal = lv_label_create(cont);
+    lv_label_set_text(label_normal, "ıTuTuTı");
+    lv_obj_set_style_text_font(label_normal, font_normal, LV_PART_MAIN);
+
+    lv_obj_t * label_none = lv_label_create(cont);
+    lv_label_set_text(label_none, "ıTuTuTı");
+    lv_obj_set_style_text_font(label_none, font_none, LV_PART_MAIN);
+
+    TEST_ASSERT_EQUAL_SCREENSHOT("tiny_ttf_2.png");
+
+    lv_obj_del(cont);
+    lv_tiny_ttf_destroy(font_normal);
+    lv_tiny_ttf_destroy(font_none);
 #else
    TEST_PASS();
 #endif