Tests: Add BLF tests

BLF tests for font file opening, display name, metrics, variable
weight changing, width, height, advances, etc. Also tests for current
minimal word wrapping.

Pull Request: https://projects.blender.org/blender/blender/pulls/135891

source/blender/blenfont/CMakeLists.txt

@@ -61,3 +61,15 @@ endif()
 
 blender_add_lib(bf_blenfont "${SRC}" "${INC}" "${INC_SYS}" "${LIB}")
 add_library(bf::blenfont ALIAS bf_blenfont)
+
+if(WITH_GTESTS)
+  set(TEST_SRC
+    tests/BLF_tests.cc
+  )
+  set(TEST_INC
+  )
+  set(TEST_LIB
+    bf::blenfont
+  )
+  blender_add_test_suite_lib(blenfont "${TEST_SRC}" "${INC};${TEST_INC}" "${INC_SYS}" "${LIB};${TEST_LIB}")
+endif()

source/blender/blenfont/tests/BLF_tests.cc

@@ -0,0 +1,248 @@
+/* SPDX-FileCopyrightText: 2025 Blender Authors
+ *
+ * SPDX-License-Identifier: Apache-2.0 */
+
+#include "BLF_api.hh"
+#include "BLI_path_utils.hh"
+#include "testing/testing.h"
+
+namespace blender::tests {
+
+static std::string font_path(std::string font_name)
+{
+  char path[FILE_MAX];
+  BLI_path_join(path,
+                sizeof(path),
+                blender::tests::flags_test_asset_dir().c_str(),
+                "blenfont",
+                font_name.c_str());
+  return std::string(path);
+}
+
+static int open_font(std::string font_name)
+{
+  BLF_init();
+  return BLF_load(font_path(font_name).c_str());
+}
+
+static void close_font(int id)
+{
+  BLF_unload_id(id);
+  BLF_exit();
+}
+
+TEST(blf_load, load)
+{
+  const int id = open_font("Ahem.ttf");
+  EXPECT_TRUE(id != -1);
+  close_font(id);
+}
+
+TEST(blf_load, font_is_loaded_path)
+{
+  BLF_init();
+  std::string path = font_path("Ahem.ttf");
+  const int id = BLF_load(path.c_str());
+  EXPECT_TRUE(BLF_is_loaded(path.c_str()));
+  close_font(id);
+}
+
+TEST(blf_load, font_is_loaded_id)
+{
+  const int id = open_font("Ahem.ttf");
+  EXPECT_TRUE(BLF_is_loaded_id(id));
+  close_font(id);
+}
+
+TEST(blf_load, display_name_from_file)
+{
+  std::string path = font_path("Ahem.ttf");
+  const char *name = BLF_display_name_from_file(path.c_str());
+  EXPECT_TRUE(STREQ(name, "Ahem Regular"));
+  /* BLF_display_name result must be freed. */
+  MEM_freeN(name);
+}
+
+TEST(blf_load, display_name_from_id)
+{
+  const int id = open_font("Ahem.ttf");
+  const char *name = BLF_display_name_from_id(id);
+  EXPECT_TRUE(STREQ(name, "Ahem Regular"));
+  /* BLF_display_name result must be freed. */
+  MEM_freeN(name);
+  close_font(id);
+}
+
+TEST(blf_load, has_glyph)
+{
+  const int id = open_font("Ahem.ttf");
+  const bool has_glyph = BLF_has_glyph(id, 0x0058); /* 'X' */
+  EXPECT_TRUE(has_glyph);
+  close_font(id);
+}
+
+TEST(blf_metrics, get_vfont_metrics)
+{
+  const int id = open_font("Ahem.ttf");
+  float ascend_ratio = 0.0f;
+  float em_ratio = 0.0f;
+  float scale = 0.0f;
+  const bool has_metrics = BLF_get_vfont_metrics(id, &ascend_ratio, &em_ratio, &scale);
+  EXPECT_TRUE(has_metrics);
+  EXPECT_TRUE(ascend_ratio == 0.8f);
+  EXPECT_TRUE(em_ratio == 1.0f);
+  EXPECT_TRUE(scale == 0.001f);
+  close_font(id);
+}
+
+TEST(blf_metrics, default_weight)
+{
+  const int id = open_font("Ahem.ttf");
+  const int weight = BLF_default_weight(id);
+  EXPECT_TRUE(weight == 400);
+  close_font(id);
+}
+
+TEST(blf_metrics, has_variable_weight)
+{
+  const int id = open_font("Roboto.ttf");
+  const bool has_variable_weight = BLF_has_variable_weight(id);
+  EXPECT_TRUE(has_variable_weight);
+  close_font(id);
+}
+
+TEST(blf_metrics, variable_weight)
+{
+  const int id = open_font("Roboto.ttf");
+  const char sample[] = "MM";
+  BLF_size(id, 100.0f);
+  BLF_character_weight(id, 300);
+  const float width_thin = BLF_width(id, sample, sizeof(sample));
+  BLF_character_weight(id, 600);
+  const float width_wide = BLF_width(id, sample, sizeof(sample));
+  EXPECT_TRUE(width_wide > width_thin);
+  close_font(id);
+}
+
+TEST(blf_dimensions, width_max)
+{
+  const int id = open_font("Ahem.ttf");
+  BLF_size(id, 100.0f);
+  const int width = BLF_width_max(id);
+  EXPECT_TRUE(width == 100.0f);
+  close_font(id);
+}
+
+TEST(blf_dimensions, height_max)
+{
+  const int id = open_font("Ahem.ttf");
+  BLF_size(id, 100.0f);
+  const int height = BLF_height_max(id);
+  EXPECT_TRUE(height == 100.0f);
+  close_font(id);
+}
+
+TEST(blf_dimensions, descender)
+{
+  const int id = open_font("Ahem.ttf");
+  BLF_size(id, 100.0f);
+  const int descender = BLF_descender(id);
+  EXPECT_TRUE(descender == -20);
+  close_font(id);
+}
+
+TEST(blf_dimensions, ascender)
+{
+  const int id = open_font("Ahem.ttf");
+  BLF_size(id, 100.0f);
+  const int ascender = BLF_ascender(id);
+  EXPECT_TRUE(ascender == 80);
+  close_font(id);
+}
+
+TEST(blf_dimensions, fixed_width)
+{
+  /* Ahem does not have all the characters needed for calculation. */
+  const int id = open_font("Roboto.ttf");
+  BLF_size(id, 100.0f);
+  const float width = BLF_fixed_width(id);
+  EXPECT_TRUE(width == 56.0f);
+  close_font(id);
+}
+
+TEST(blf_dimensions, width_em)
+{
+  /* In this test font, 'X' is exactly one em wide. */
+  const char sample[] = "XX";
+  int id = open_font("Ahem.ttf");
+  BLF_size(id, 100.0f);
+  const float width = BLF_width(id, sample, sizeof(sample));
+  EXPECT_TRUE(width == 200.0f);
+  close_font(id);
+}
+
+TEST(blf_dimensions, height_em)
+{
+  /* In this test font, 'X' is exactly one em high. */
+  const char sample[] = "X";
+  int id = open_font("Ahem.ttf");
+  BLF_size(id, 100.0f);
+  const float width = BLF_height(id, sample, sizeof(sample));
+  EXPECT_TRUE(width == 100.0f);
+  close_font(id);
+}
+
+TEST(blf_dimensions, advance)
+{
+  /* In this test font, 'X' has advance of exactly one em. */
+  const char sample[] = "X";
+  int id = open_font("Ahem.ttf");
+  BLF_size(id, 100.0f);
+  const float width = BLF_glyph_advance(id, sample);
+  EXPECT_NEAR(width, 100.0f, 0.000001f);
+  close_font(id);
+}
+
+TEST(blf_wrapping_minimal, wrap_overflow_ascii)
+{
+  /* Do not break, even though over the wrap limit. */
+  const char sample[] =
+      "xxxxxxxxxxxxxxxxxxx!\"#$%&\'()*+,-./"
+      "0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~";
+  /* Ahem does not contain all the characters included in above string. */
+  int id = open_font("Roboto.ttf");
+  BLF_size(id, 10.0f);
+  const float width = BLF_width(id, sample, sizeof(sample));
+  blender::Vector<blender::StringRef> wrapped = BLF_string_wrap(
+      id, sample, int(float(width) * 0.05f));
+  EXPECT_TRUE(wrapped.size() == 1 && (strlen(sample) == wrapped[0].size()));
+  close_font(id);
+}
+
+TEST(blf_wrapping_minimal, wrap_space)
+{
+  /* Must break at the center spaces into two, one space trailing, one leading. */
+  const char sample[] = "x xxxxxxxxxxxxxxxx  xxxxxxxxxxxxxxxxxxx ";
+  int id = open_font("Ahem.ttf");
+  BLF_size(id, 10.0f);
+  const float width = BLF_width(id, sample, sizeof(sample));
+  blender::Vector<blender::StringRef> wrapped = BLF_string_wrap(
+      id, sample, int(float(width) * 0.7f));
+  EXPECT_TRUE(wrapped.size() == 2 && wrapped[0].back() == ' ' && wrapped[1].substr(0, 1) != " ");
+  close_font(id);
+}
+
+TEST(blf_wrapping_minimal, wrap_linefeed)
+{
+  /* Must break on every line feed except at end of string. */
+  const char sample[] = "x\nxxxxxxxxxxxxxxxx\n\nxxxxxxxxxxxxxxxxxxx\n";
+  int id = open_font("Ahem.ttf");
+  BLF_size(id, 10.0f);
+  const float width = BLF_width(id, sample, sizeof(sample));
+  blender::Vector<blender::StringRef> wrapped = BLF_string_wrap(
+      id, sample, int(float(width) * 0.7f));
+  EXPECT_TRUE(wrapped.size() == 4 && wrapped[2].is_empty());
+  close_font(id);
+}
+
+}  // namespace blender::tests