Merge pull request #9 from stissing/master

Added a lens effect

README.md

@@ -36,7 +36,7 @@ The TouchGFX version stated is the version that the component has been tested wi
   <tr>
     <td>WheelSelector <br>TouchGFX 4.2<br> <a href="widgets/WheelSelector/"> <img src="widgets/WheelSelector/days_fade_in.png" height="100"></a></td>
     <td>CircularProgress <br>TouchGFX 4.2<br> <a href="widgets/CircularProgress/"> <img src="widgets/CircularProgress/example.png" height="100"></a></td> 
-    <td></td>
+    <td>Lens <br>TouchGFX 4.2 <br><a href="widgets/Lens/"><img src="widgets/Lens/screenshots/lens-effect.png" height="100"></a></td>
   </tr>
 </table>
 

widgets/Lens/Lens.cpp

@@ -0,0 +1,105 @@
+#include <gui/common/Lens.hpp>
+#include <touchgfx/hal/HAL.hpp>
+#include <math.h>
+#include <BitmapDatabase.hpp>
+
+Lens::Lens()
+{
+	// calculate the distortion of the lens
+	// derivations of the formula can be found online, for instance in the demo effects collection at 
+	// http://demo-effects.cvs.sourceforge.net/viewvc/demo-effects/demo-effects/LENS/lens.c?view=markup
+	for (int y = 0; y < lensRadius; y++) {
+		for (int x = 0; x < lensRadius; x++) {
+			int ix, iy, offset;
+			if ((x * x + y * y) < (lensRadius * lensRadius)) 
+			{
+				float shift = lensZoom/sqrt((float)lensZoom*lensZoom - (x*x + y*y - lensRadius*lensRadius));
+				ix = (int)(x * shift - x);
+				iy = (int)(y * shift - y);
+			} 
+			else 
+			{
+				ix = 0;
+				iy = 0;
+			}
+			offset = (iy * touchgfx::HAL::DISPLAY_WIDTH + ix);
+			lens[lensRadius - y][lensRadius - x] = -offset;
+			lens[lensRadius + y][lensRadius + x] = offset;
+			offset = (-iy * touchgfx::HAL::DISPLAY_WIDTH + ix);
+			lens[lensRadius + y][lensRadius - x] = -offset;
+			lens[lensRadius - y][lensRadius + x] = offset;
+		}
+	}
+	setWidth(lensWidth);
+	setHeight(lensWidth);
+
+	lensImage.setBitmap(touchgfx::Bitmap(BITMAP_LENS_IMAGE_ID));
+}
+
+touchgfx::Rect Lens::getSolidRect() const
+{
+	return touchgfx::Rect();
+}
+
+void Lens::draw(const touchgfx::Rect& invalidatedArea) const
+{
+	uint16_t *fb = touchgfx::HAL::getInstance()->lockFrameBuffer();
+
+	touchgfx::Rect abs(0,0,getWidth(),getHeight());
+	translateRectToAbsolute(abs);
+
+	// since we both read and write the frame buffer, we split the loops in to four sections/quadrants
+	// and run through them left to right or right to left, top to bottom or bottom to top,
+	int16_t middleX = getWidth()/2;
+	int16_t middleY = getHeight()/2;
+
+	for(int y = invalidatedArea.y; y < invalidatedArea.bottom() && y <= middleY; y++)
+	{
+		for(int x = invalidatedArea.x; x < invalidatedArea.right() && x <= middleX; x++)
+		{
+			apply(fb, abs.x, abs.y, x, y);
+		}
+
+		for(int x = invalidatedArea.right()-1; x > middleX && x >= invalidatedArea.x; x--)
+		{
+			apply(fb, abs.x, abs.y, x, y);
+		}
+	}
+
+	for(int y = invalidatedArea.bottom()-1; y > middleY && y >= invalidatedArea.y; y--)
+	{
+		for(int x = invalidatedArea.x; x < invalidatedArea.right() && x <= middleX; x++)
+		{
+			apply(fb, abs.x, abs.y, x, y);
+		}
+
+		for(int x = invalidatedArea.right()-1; x > middleX && x >= invalidatedArea.x; x--)
+		{
+			apply(fb, abs.x, abs.y, x, y);
+		}
+	}
+
+	touchgfx::HAL::getInstance()->unlockFrameBuffer();
+
+	touchgfx::Rect dirtyBitmapArea = touchgfx::Bitmap(lensImage.getBitmap()).getRect() & invalidatedArea;
+	touchgfx::HAL::lcd().drawPartialBitmap(touchgfx::Bitmap(lensImage.getBitmap()), abs.x, abs.y, dirtyBitmapArea, 255);
+}
+
+void Lens::apply(uint16_t* fb, int absx, int absy, int x, int y) const
+{
+	int16_t lensOffset = lens[y][x];
+	uint32_t fbOffset = x+absx + (y+absy) * touchgfx::HAL::DISPLAY_WIDTH;
+	if((int32_t)fbOffset + lensOffset < 0)
+	{
+		fb[fbOffset] = fb[fbOffset + lensOffset + touchgfx::HAL::DISPLAY_HEIGHT*touchgfx::HAL::DISPLAY_WIDTH];
+	}
+	else if((int32_t)fbOffset + lensOffset > touchgfx::HAL::DISPLAY_HEIGHT*touchgfx::HAL::DISPLAY_WIDTH)
+	{
+		fb[fbOffset] = fb[fbOffset + lensOffset - touchgfx::HAL::DISPLAY_HEIGHT*touchgfx::HAL::DISPLAY_WIDTH];
+	}
+	else
+	{
+		fb[fbOffset] = fb[fbOffset + lensOffset];
+	}
+}
+

widgets/Lens/Lens.hpp

@@ -0,0 +1,62 @@
+#ifndef LENS_HPP
+#define LENS_HPP
+
+#include <touchgfx/widgets/Widget.hpp>
+#include <touchgfx/hal/Types.hpp>
+#include <touchgfx/widgets/Image.hpp>
+
+/**
+* @class Lens
+*
+* Lens shows a lens like effect on top of the frame buffer
+*
+* This widget is part of the TouchGFX Open Widget Repository. 
+* https://github.com/draupnergraphics/touchgfx-open-repository
+*
+* @note This version of a lens, will not draw it self correctly if solid
+*       widgets are placed on top of it. This is due to the fact that
+*       the lens uses data from the frame buffer and the data 
+*       below the lens (and the solid widgets) will not be updated in this case
+*
+* @sa touchgfx::Widget
+*/
+class Lens : public touchgfx::Widget
+{
+public:
+	/**
+	* @fn Lens::Lens();
+	*
+	* @brief initializes the lens data
+	*/
+	Lens();
+
+	/**
+	* @fn virtual touchgfx::Rect Lens::getSolidRect() const;
+	*
+	* @brief Report the solid dimensions of this widget. 
+	*        As we would like the frame buffer below to be drawn, 
+	*        the widget is reported as transparent
+	*        
+	* @return an empty rectangle.
+	*/
+	virtual touchgfx::Rect getSolidRect() const;
+
+	/**
+	* @fn virtual void Lens::draw(const touchgfx::Rect& invalidatedArea) const;
+	*
+	* @brief read, distort and write the frame buffer contents.
+	*
+	* @param invalidatedArea The part of the widget that should be drawn.
+	*/
+	virtual void draw(const touchgfx::Rect& invalidatedArea) const;
+private:
+	void apply(uint16_t* fb, int absx, int absy, int x, int y) const;
+
+	static const uint8_t lensRadius = 100;
+	static const uint8_t lensWidth = 2*lensRadius;
+	static const uint8_t lensZoom = 40;
+	int16_t lens[lensWidth][lensWidth]; //note: move the lens data to flash
+	touchgfx::Image lensImage;
+};
+
+#endif

widgets/Lens/README.md

@@ -0,0 +1,27 @@
+Purpose
+========
+
+![example](screenshots/lens-effect.png "Resulting lens effect")
+
+The purpose of the Lens is to provide an effect on top of already existing graphics. The lens will distort the contents below it. 
+
+The lens has a radius of 100. This number can be adjusted. 
+
+The lens adds an image of a semi transparent glass on top of the distorted graphics. If the radius of the lens is adjusted, additional image data may be needed for the glass.
+
+![glass](assets/lens_image.png "Glass")
+
+Note that the lens is more dependent on the contents of the framebuffer and therefore the order of drawing than more regular widgets.
+
+TouchGFX Version
+=================
+
+This widget was created and tested using TouchGFX version 4.2.0
+
+Functional description
+======================
+
+Add the lens to a view. 
+
+
+