Imgui can be now downscaled to fit small resolution screens.

examples/common/imgui/imgui.cpp

@@ -388,6 +388,8 @@ struct Imgui
 		, m_halfTexel(0.0f)
 		, m_nvg(NULL)
 		, m_view(255)
+		, m_surfaceWidth(0)
+		, m_surfaceHeight(0)
 		, m_viewWidth(0)
 		, m_viewHeight(0)
 		, m_currentFontIdx(0)
@@ -810,21 +812,31 @@ struct Imgui
 		m_char = _inputChar;
 	}
 
-	void beginFrame(int32_t _mx, int32_t _my, uint8_t _button, int32_t _scroll, uint16_t _width, uint16_t _height, char _inputChar, uint8_t _view)
+	void beginFrame(int32_t _mx, int32_t _my, uint8_t _button, int32_t _scroll, uint16_t _width, uint16_t _height, uint16_t _surfaceWidth, uint16_t _surfaceHeight, char _inputChar, uint8_t _view)
 	{
-		IMGUI_beginFrame(_mx, _my, _button, _width, _height, _inputChar, _view);
-		nvgViewId(m_nvg, _view);
-
 		m_view = _view;
 		m_viewWidth = _width;
 		m_viewHeight = _height;
+		m_surfaceWidth = _surfaceWidth;
+		m_surfaceHeight = _surfaceHeight;
+
+		const float xscale = float(m_surfaceWidth) /float(m_viewWidth);
+		const float yscale = float(m_surfaceHeight)/float(m_viewHeight);
+		const int32_t mx = int32_t(float(_mx)*xscale);
+		const int32_t my = int32_t(float(_my)*yscale);
+
+		IMGUI_beginFrame(mx, my, _button, _width, _height, _inputChar, _view);
+		nvgBeginFrameScaled(m_nvg, m_viewWidth, m_viewHeight, m_surfaceWidth, m_surfaceHeight, 1.0f);
+		nvgViewId(m_nvg, _view);
+
 		bgfx::setViewName(_view, "IMGUI");
 		bgfx::setViewSeq(_view, true);
 
 		const bgfx::HMD* hmd = bgfx::getHMD();
 		if (NULL != hmd)
 		{
-			m_viewWidth  = _width / 2;
+			m_viewWidth = _width / 2;
+			m_surfaceWidth = _surfaceWidth / 2;
 
 			float proj[16];
 			bx::mtxProj(proj, hmd->eye[0].fov, 0.1f, 100.0f);
@@ -837,22 +849,22 @@ struct Imgui
 			const float offset1 = -proj[8] + (hmd->eye[1].viewOffset[0] / dist * proj[0]);
 
 			float ortho[2][16];
-			const float viewOffset = _width/4.0f;
-			const float viewWidth  = _width/2.0f;
-			bx::mtxOrtho(ortho[0], viewOffset, viewOffset + viewWidth, (float)m_viewHeight, 0.0f, 0.0f, 1000.0f, offset0);
-			bx::mtxOrtho(ortho[1], viewOffset, viewOffset + viewWidth, (float)m_viewHeight, 0.0f, 0.0f, 1000.0f, offset1);
+			const float viewOffset = _surfaceWidth/4.0f;
+			const float viewWidth  = _surfaceWidth/2.0f;
+			bx::mtxOrtho(ortho[0], viewOffset, viewOffset + viewWidth, (float)m_surfaceHeight, 0.0f, 0.0f, 1000.0f, offset0);
+			bx::mtxOrtho(ortho[1], viewOffset, viewOffset + viewWidth, (float)m_surfaceHeight, 0.0f, 0.0f, 1000.0f, offset1);
 			bgfx::setViewTransform(_view, NULL, ortho[0], BGFX_VIEW_STEREO, ortho[1]);
 			bgfx::setViewRect(_view, 0, 0, hmd->width, hmd->height);
 		}
 		else
 		{
 			float ortho[16];
-			bx::mtxOrtho(ortho, 0.0f, (float)m_viewWidth, (float)m_viewHeight, 0.0f, 0.0f, 1000.0f);
+			bx::mtxOrtho(ortho, 0.0f, (float)m_surfaceWidth, (float)m_surfaceHeight, 0.0f, 0.0f, 1000.0f);
 			bgfx::setViewTransform(_view, NULL, ortho);
 			bgfx::setViewRect(_view, 0, 0, _width, _height);
 		}
 
-		updateInput(_mx, _my, _button, _scroll, _inputChar);
+		updateInput(mx, my, _button, _scroll, _inputChar);
 
 		m_hot = m_hotToBe;
 		m_hotToBe = 0;
@@ -884,6 +896,7 @@ struct Imgui
 
 		clearInput();
 
+		nvgEndFrame(m_nvg);
 		IMGUI_endFrame();
 	}
 
@@ -937,12 +950,7 @@ struct Imgui
 			setEnabled(m_areaId);
 		}
 
-		nvgScissor(m_nvg
-				 , float(area.m_scissorX)
-				 , float(area.m_scissorY-1)
-				 , float(area.m_scissorWidth)
-				 , float(area.m_scissorHeight+1)
-				 );
+		nvgScissor(m_nvg, area);
 
 		m_insideArea |= area.m_inside;
 
@@ -1080,12 +1088,7 @@ struct Imgui
 			}
 		}
 
-		nvgScissor(m_nvg
-				 , float(parentArea.m_scissorX)
-				 , float(parentArea.m_scissorY-1)
-				 , float(parentArea.m_scissorWidth)
-				 , float(parentArea.m_scissorHeight+1)
-				 );
+		nvgScissor(m_nvg, parentArea);
 	}
 
 	bool beginArea(const char* _name, int32_t _x, int32_t _y, int32_t _width, int32_t _height, bool _enabled, int32_t _r)
@@ -1159,13 +1162,7 @@ struct Imgui
 		}
 		area.m_scissorEnabled = true;
 
-		nvgBeginFrame(m_nvg, m_viewWidth, m_viewHeight, 1.0f);
-		nvgScissor(m_nvg
-				 , float(area.m_scissorX)
-				 , float(area.m_scissorY-1)
-				 , float(area.m_scissorWidth)
-				 , float(area.m_scissorHeight+1)
-				 );
+		nvgScissor(m_nvg, area);
 
 		m_insideArea |= area.m_inside;
 		return area.m_inside;
@@ -1175,7 +1172,6 @@ struct Imgui
 	{
 		m_areaId.pop();
 		nvgResetScissor(m_nvg);
-		nvgEndFrame(m_nvg);
 	}
 
 	bool button(const char* _text, bool _enabled, ImguiAlign::Enum _align, uint32_t _rgb0, int32_t _r)
@@ -1204,7 +1200,7 @@ struct Imgui
 			 //||  ImguiAlign::CenterIndented == _align).
 		{
 			xx = area.m_widgetX;
-			width = area.m_widgetW - (area.m_widgetX-area.m_scissorX);
+			width = area.m_widgetW - (area.m_widgetX-area.m_contentX);
 		}
 
 		const bool enabled = _enabled && isEnabled(m_areaId);
@@ -1387,7 +1383,7 @@ struct Imgui
 			 //||  ImguiAlign::CenterIndented == _align).
 		{
 			xx = area.m_widgetX;
-			width = area.m_widgetW - (area.m_widgetX-area.m_scissorX);
+			width = area.m_widgetW - (area.m_widgetX-area.m_contentX);
 		}
 
 		const bool drawLabel = (NULL != _label && _label[0] != '\0');
@@ -1526,7 +1522,7 @@ struct Imgui
 			 //||  ImguiAlign::CenterIndented == _align).
 		{
 			xx = area.m_widgetX;
-			width = area.m_widgetW - (area.m_widgetX-area.m_scissorX);
+			width = area.m_widgetW - (area.m_widgetX-area.m_contentX);
 		}
 
 		uint8_t selected = _selected;
@@ -1746,7 +1742,7 @@ struct Imgui
 			 //||  ImguiAlign::CenterIndented == _align).
 		{
 			xx = area.m_widgetX;
-			width = area.m_widgetW - (area.m_widgetX-area.m_scissorX);
+			width = area.m_widgetW - (area.m_widgetX-area.m_contentX);
 		}
 
 		const int32_t height = width/2;
@@ -1799,7 +1795,7 @@ struct Imgui
 			 //||  ImguiAlign::CenterIndented == _align).
 		{
 			xx = area.m_widgetX;
-			width = area.m_widgetW - (area.m_widgetX-area.m_scissorX);
+			width = area.m_widgetW - (area.m_widgetX-area.m_contentX);
 		}
 
 		const bool adjustHeight = (_cross && _sameHeight);
@@ -2025,39 +2021,39 @@ struct Imgui
 			xx = -borderSize;
 			yy = -1;
 			width = 2*borderSize+1;
-			height = m_viewHeight+1;
+			height = m_surfaceHeight+1;
 			triX = 0;
-			triY = (m_viewHeight-triSize)/2;
+			triY = (m_surfaceHeight-triSize)/2;
 			orientation = _checked ? TriangleOrientation::Left : TriangleOrientation::Right;
 		}
 		else if (ImguiBorder::Right == _border)
 		{
-			xx = m_viewWidth - borderSize;
+			xx = m_surfaceWidth - borderSize;
 			yy = -1;
 			width = 2*borderSize+1;
-			height = m_viewHeight+1;
-			triX = m_viewWidth - triSize - 2;
-			triY = (m_viewHeight-width)/2;
+			height = m_surfaceHeight+1;
+			triX = m_surfaceWidth - triSize - 2;
+			triY = (m_surfaceHeight-width)/2;
 			orientation = _checked ? TriangleOrientation::Right : TriangleOrientation::Left;
 		}
 		else if (ImguiBorder::Top == _border)
 		{
 			xx = 0;
 			yy = -borderSize;
-			width = m_viewWidth;
+			width = m_surfaceWidth;
 			height = 2*borderSize;
-			triX = (m_viewWidth-triSize)/2;
+			triX = (m_surfaceWidth-triSize)/2;
 			triY = 0;
 			orientation = _checked ? TriangleOrientation::Up : TriangleOrientation::Down;
 		}
 		else //if (ImguiBorder::Bottom == _border).
 		{
 			xx = 0;
-			yy = m_viewHeight - borderSize;
-			width = m_viewWidth;
+			yy = m_surfaceHeight - borderSize;
+			width = m_surfaceWidth;
 			height = 2*borderSize;
-			triX = (m_viewWidth-triSize)/2;
-			triY = m_viewHeight-triSize;
+			triX = (m_surfaceWidth-triSize)/2;
+			triY = m_surfaceHeight-triSize;
 			orientation = _checked ? TriangleOrientation::Down : TriangleOrientation::Up;
 		}
 
@@ -2148,7 +2144,7 @@ struct Imgui
 			 //||  ImguiAlign::CenterIndented == _align).
 		{
 			xx = area.m_widgetX;
-			width = area.m_widgetW - (area.m_widgetX-area.m_scissorX);
+			width = area.m_widgetW - (area.m_widgetX-area.m_contentX);
 		}
 
 		drawRoundedRect( (float)xx, (float)yy, (float)width, (float)height, 4.0f, imguiRGBA(0, 0, 0, 128) );
@@ -3049,10 +3045,16 @@ struct Imgui
 		const Area& area = getCurrentArea();
 		if (area.m_scissorEnabled)
 		{
-			bgfx::setScissor(uint16_t(IMGUI_MAX(0, area.m_scissorX) )
-						   , uint16_t(IMGUI_MAX(0, area.m_scissorY-1) )
-						   , area.m_scissorWidth
-						   , area.m_scissorHeight+1
+			const float xscale = float(m_viewWidth) /float(m_surfaceWidth);
+			const float yscale = float(m_viewHeight)/float(m_surfaceHeight);
+			const int16_t scissorX      = int16_t(float(area.m_scissorX)*xscale);
+			const int16_t scissorY      = int16_t(float(area.m_scissorY)*yscale);
+			const int16_t scissorWidth  = int16_t(float(area.m_scissorWidth)*xscale);
+			const int16_t scissorHeight = int16_t(float(area.m_scissorHeight)*yscale);
+			bgfx::setScissor(uint16_t(IMGUI_MAX(0, scissorX) )
+						   , uint16_t(IMGUI_MAX(0, scissorY-1) )
+						   , scissorWidth
+						   , scissorHeight+1
 						   );
 		}
 		else
@@ -3061,6 +3063,23 @@ struct Imgui
 		}
 	}
 
+	inline void nvgScissor(NVGcontext* _ctx, const Area& _area)
+	{
+		if (_area.m_scissorEnabled)
+		{
+			::nvgScissor(_ctx
+						, float(IMGUI_MAX(0, _area.m_scissorX) )
+						, float(IMGUI_MAX(0, _area.m_scissorY-1) )
+						, float(_area.m_scissorWidth)
+						, float(_area.m_scissorHeight+1)
+						);
+		}
+		else
+		{
+			nvgResetScissor(_ctx);
+		}
+	}
+
 	template <typename Ty, uint16_t Max=64>
 	struct IdStack
 	{
@@ -3150,6 +3169,8 @@ struct Imgui
 	uint8_t m_view;
 	uint16_t m_viewWidth;
 	uint16_t m_viewHeight;
+	uint16_t m_surfaceWidth;
+	uint16_t m_surfaceHeight;
 
 #if !USE_NANOVG_FONT
 	struct Font
@@ -3204,9 +3225,14 @@ ImguiFontHandle imguiGetCurrentFont()
 	return handle;
 }
 
+void imguiBeginFrame(int32_t _mx, int32_t _my, uint8_t _button, int32_t _scroll, uint16_t _width, uint16_t _height, uint16_t _surfaceWidth, uint16_t _surfaceHeight, char _inputChar, uint8_t _view)
+{
+	s_imgui.beginFrame(_mx, _my, _button, _scroll, _width, _height, _surfaceWidth, _surfaceHeight, _inputChar, _view);
+}
+
 void imguiBeginFrame(int32_t _mx, int32_t _my, uint8_t _button, int32_t _scroll, uint16_t _width, uint16_t _height, char _inputChar, uint8_t _view)
 {
-	s_imgui.beginFrame(_mx, _my, _button, _scroll, _width, _height, _inputChar, _view);
+	s_imgui.beginFrame(_mx, _my, _button, _scroll, _width, _height, _width, _height, _inputChar, _view);
 }
 
 void imguiEndFrame()

examples/common/imgui/imgui.h

@@ -137,6 +137,7 @@ ImguiFontHandle imguiCreate(const void* _data = NULL, uint32_t _size = 0, float
 void imguiDestroy();
 
 void imguiBeginFrame(int32_t _mx, int32_t _my, uint8_t _button, int32_t _scroll, uint16_t _width, uint16_t _height, char _inputChar = 0, uint8_t _view = 255);
+void imguiBeginFrame(int32_t _mx, int32_t _my, uint8_t _button, int32_t _scroll, uint16_t _width, uint16_t _height, uint16_t _surfaceWidth, uint16_t _surfaceHeight, char _inputChar = 0, uint8_t _view = 255);
 void imguiEndFrame();
 
 void imguiDrawText(int _x, int _y, ImguiTextAlign::Enum _align, const char* _text, uint32_t _argb);

examples/common/nanovg/nanovg.cpp

@@ -296,7 +296,7 @@ void nvgDeleteInternal(NVGcontext* ctx)
 	free(ctx);
 }
 
-void nvgBeginFrame(NVGcontext* ctx, int windowWidth, int windowHeight, float devicePixelRatio)
+void nvgBeginFrameScaled(NVGcontext* ctx, int windowWidth, int windowHeight, int surfaceWidth, int surfaceHeight, float devicePixelRatio)
 {
 /*	printf("Tris: draws:%d  fill:%d  stroke:%d  text:%d  TOT:%d\n",
 		ctx->drawCallCount, ctx->fillTriCount, ctx->strokeTriCount, ctx->textTriCount,
@@ -307,8 +307,8 @@ void nvgBeginFrame(NVGcontext* ctx, int windowWidth, int windowHeight, float dev
 	nvgReset(ctx);
 
 	nvg__setDevicePixelRatio(ctx, devicePixelRatio);
-	
-	ctx->params.renderViewport(ctx->params.userPtr, windowWidth, windowHeight);
+
+	ctx->params.renderViewport(ctx->params.userPtr, windowWidth, windowHeight, surfaceWidth, surfaceHeight);
 
 	ctx->drawCallCount = 0;
 	ctx->fillTriCount = 0;
@@ -316,6 +316,11 @@ void nvgBeginFrame(NVGcontext* ctx, int windowWidth, int windowHeight, float dev
 	ctx->textTriCount = 0;
 }
 
+void nvgBeginFrame(NVGcontext* ctx, int windowWidth, int windowHeight, float devicePixelRatio)
+{
+	nvgBeginFrameScaled(ctx, windowWidth, windowHeight, windowWidth, windowHeight, devicePixelRatio);
+}
+
 void nvgCancelFrame(NVGcontext* ctx)
 {
 	ctx->params.renderCancel(ctx->params.userPtr);

examples/common/nanovg/nanovg.h

@@ -116,6 +116,7 @@ enum NVGimageFlags {
 // frame buffer size. In that case you would set windowWidth/Height to the window size
 // devicePixelRatio to: frameBufferWidth / windowWidth.
 void nvgBeginFrame(NVGcontext* ctx, int windowWidth, int windowHeight, float devicePixelRatio);
+void nvgBeginFrameScaled(NVGcontext* ctx, int windowWidth, int windowHeight, int surfaceWidth, int surfaceHeight, float devicePixelRatio);
 
 // Cancels drawing the current frame.
 void nvgCancelFrame(NVGcontext* ctx);
@@ -588,7 +589,7 @@ struct NVGparams {
 	int (*renderDeleteTexture)(void* uptr, int image);
 	int (*renderUpdateTexture)(void* uptr, int image, int x, int y, int w, int h, const unsigned char* data);
 	int (*renderGetTextureSize)(void* uptr, int image, int* w, int* h);
-	void (*renderViewport)(void* uptr, int width, int height);
+	void (*renderViewport)(void* uptr, int width, int height, int surfaceWidth, int surfaceHeight);
 	void (*renderCancel)(void* uptr);
 	void (*renderFlush)(void* uptr);
 	void (*renderFill)(void* uptr, NVGpaint* paint, NVGscissor* scissor, float fringe, const float* bounds, const NVGpath* paths, int npaths);

examples/common/nanovg/nanovg_bgfx.cpp

@@ -132,6 +132,7 @@ namespace
 
 		struct GLNVGtexture* textures;
 		float view[2];
+		float surface[2];
 		int ntextures;
 		int ctextures;
 		int textureId;
@@ -516,11 +517,13 @@ namespace
 		gl->th = handle;
 	}
 
-	static void nvgRenderViewport(void* _userPtr, int width, int height)
+	static void nvgRenderViewport(void* _userPtr, int width, int height, int surfaceWidth, int surfaceHeight)
 	{
 		struct GLNVGcontext* gl = (struct GLNVGcontext*)_userPtr;
 		gl->view[0] = (float)width;
 		gl->view[1] = (float)height;
+		gl->surface[0] = (float)surfaceWidth;
+		gl->surface[1] = (float)surfaceHeight;
 		bgfx::setViewRect(gl->viewid, 0, 0, width, height);
 	}
 
@@ -720,7 +723,7 @@ namespace
 								);
 			}
 
-			bgfx::setUniform(gl->u_viewSize, gl->view);
+			bgfx::setUniform(gl->u_viewSize, gl->surface);
 
 			for (uint32_t ii = 0, num = gl->ncalls; ii < num; ++ii)
 			{