fix blurry font issue when the DPI scale > 1.0 #65

Author: liuping

pkg/ant.imgui/main.lua

@@ -30,6 +30,7 @@ function ImGuiAnt.FontAtlasBuild(list)
         FontDatas[#FontDatas+1] = FontData
         local data, size = fastio.wrap(FontData)()
         ImFontConfig.MergeMode = i > 1
+        ImFontConfig.RasterizerDensity = config.RasterizerDensity
         atlas.AddFontFromMemoryTTF(data, size, config.SizePixels, ImFontConfig, glyphRanges(config.GlyphRanges))
     end
     atlas.Build()

tools/editor/pkg/tools.editor/init_system.lua

@@ -21,6 +21,10 @@ local widget_utils      = require "widget.utils"
 
 local m = ecs.system 'init_system'
 
+local ImGui         = require "imgui"
+local ImGuiBackend  = require "imgui.backend"
+local ImGuiDPIScale = 1
+
 local function start_fileserver(luaexe, path)
 	local fsa = require "fileserver_adapter"
 	fsa.init(luaexe, path)
@@ -32,11 +36,13 @@ local function init_font()
 	fonts[#fonts+1] = {
 		FontPath = "/pkg/ant.resources.binary/font/Alibaba-PuHuiTi-Regular.ttf",
 		SizePixels = 18,
+		RasterizerDensity = ImGuiDPIScale,
 		GlyphRanges = { 0x0020, 0xFFFF }
 	}
 	fonts[#fonts+1] = {
 		FontPath = "/pkg/tools.editor/resource/fonts/fa-solid-900.ttf",
 		SizePixels = 16,
+		RasterizerDensity = ImGuiDPIScale,
 		GlyphRanges = {
 			0xf062, 0xf062, -- ICON_FA_ARROW_UP 			"\xef\x81\xa2"	U+f062
 			0xf063, 0xf063,	-- ICON_FA_ARROW_DOWN 			"\xef\x81\xa3"	U+f063
@@ -155,6 +161,32 @@ function m:data_changed()
 
 end
 
+local dpi_scale_range = {min=0.0, max=2.77, value=1, enabled=true}
+function m:start_frame()
+    -- GetWindowDpiScale/GetMainViewport only availbled in start_frame/end_frame
+    if dpi_scale_range.enabled then
+        dpi_scale_range.value = ImGui.GetWindowDpiScale()
+    end
+end
+
+function m:final()
+    -- ImGui says: Can not modify a locked ImFontAtlas between NewFrame() and EndFrame/Render()
+    if dpi_scale_range.enabled then
+        -- calculate DPI scale
+        local min = dpi_scale_range.min
+        local max = dpi_scale_range.max
+        local value = dpi_scale_range.value
+        ImGuiDPIScale = math.max(min, math.min(max, value))
+        dpi_scale_range.enabled = false
+
+        -- rebuild font atlas
+        init_font()
+        ImGuiBackend.RenderCreateFontsTexture()
+
+        log.warn(string.format('rebuild the font atlas due to the DPI scale changed dpi:1.0->%.2f', value))
+    end
+end
+
 function m:exit()
 	if global_data.fileserver and global_data.fileserver.subprocess then
 		global_data.fileserver.subprocess:wait()