Bodmer
0e0fd75277
The library has been cleaned up as it has got a bit untidy due to the large number of small incremental changes. 4bit Sprite examples renaed to be consistent with others. alphaBlend example moved to generic folder (alphaBlend fn was moved to TFT_eSPI class). Added sections + explanatory comments to functions prototypes. Temporary comments added for potential gotchas for noobs when using DMA. spi_begin/end functions renamed to reflect functionality. Old fns retained for backwards compatibility with user setup.h files.
195 lines
6.7 KiB
Arduino
195 lines
6.7 KiB
Arduino
/*
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This tests the alpha blending function that is used with the antialiased
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fonts:
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Alpha = 0 = 100% background, alpha = 255 = 100% foreground colour
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blendedColor = tft.alphaBlend(alpha, fg_color, bg_color);
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The alphaBlend() function operates on 16 bit colours only
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A test is included where the colours are mapped to 8 bits after blending
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Information on alpha blending is here
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https://en.wikipedia.org/wiki/Alpha_compositing
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Example for library:
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https://github.com/Bodmer/TFT_eSPI
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The sketch has been tested on a 320x240 ILI9341 based TFT, it
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could be adapted for other screen sizes.
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Created by Bodmer 10/2/18
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#########################################################################
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###### DON'T FORGET TO UPDATE THE User_Setup.h FILE IN THE LIBRARY ######
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#########################################################################
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*/
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#include <TFT_eSPI.h> // Include the graphics library
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TFT_eSPI tft = TFT_eSPI(); // Create object "tft"
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// -------------------------------------------------------------------------
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// Setup
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// -------------------------------------------------------------------------
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void setup(void) {
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tft.init();
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tft.setRotation(0);
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tft.fillScreen(TFT_DARKGREY);
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}
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// -------------------------------------------------------------------------
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// Main loop
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// -------------------------------------------------------------------------
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void loop()
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{
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// 16 bit colours (5 bits red, 6 bits green, 5 bits blue)
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// Blend from white to full spectrum
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for (int a = 0; a < 256; a+=2) // Alpha 0 = 100% background, alpha 255 = 100% foreground
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{
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for (int c = 0; c < 192; c++) tft.drawPixel(c, a/2, tft.alphaBlend(a, rainbow(c), TFT_WHITE));
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}
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// Blend from full spectrum to black
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for (int a = 255; a > 2; a-=2)
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{
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for (int c = 0; c < 192; c++) tft.drawPixel(c, 128 + (255-a)/2, tft.alphaBlend(a, rainbow(c), TFT_BLACK));
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}
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// Blend from white to black (32 grey levels)
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for (uint16_t a = 0; a < 255; a++) // Alpha 0 = 100% background, alpha 255 = 100% foreground
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{
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tft.drawFastHLine(192, a, 12, tft.alphaBlend(a, TFT_BLACK, TFT_WHITE));
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tft.drawFastHLine(204, a, 12, tft.alphaBlend(a, TFT_BLACK, TFT_RED));
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tft.drawFastHLine(216, a, 12, tft.alphaBlend(a, TFT_BLACK, TFT_GREEN));
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tft.drawFastHLine(228, a, 12, tft.alphaBlend(a, TFT_BLACK, TFT_BLUE));
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}
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delay(4000);
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// Blend from white to colour (32 grey levels)
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for (uint16_t a = 0; a < 255; a++) // Alpha 0 = 100% background, alpha 255 = 100% foreground
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{
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//tft.drawFastHLine(192, a, 12, tft.alphaBlend(a, TFT_BLACK, TFT_WHITE));
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tft.drawFastHLine(204, a, 12, tft.alphaBlend(a, TFT_RED, TFT_WHITE));
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tft.drawFastHLine(216, a, 12, tft.alphaBlend(a, TFT_GREEN, TFT_WHITE));
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tft.drawFastHLine(228, a, 12, tft.alphaBlend(a, TFT_BLUE, TFT_WHITE));
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}
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delay(4000);
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//*
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// Decrease to 8 bit colour (3 bits red, 3 bits green, 2 bits blue)
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// Blend from white to full spectrum
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for (int a = 0; a < 256; a+=2) // Alpha 0 = 100% background, alpha 255 = 100% foreground
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{
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// Convert blended 16 bit colour to 8 bits to reduce colour resolution, then map back to 16 bits for displaying
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for (int c = 0; c < 192; c++) tft.drawPixel(c, a/2, tft.color8to16(tft.color16to8(tft.alphaBlend(a, rainbow(c), 0xFFFF))));
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}
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// Blend from full spectrum to black
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for (int a = 255; a > 2; a-=2)
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{
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// Convert blended 16 bit colour to 8 bits to reduce colour resolution, then map back to 16 bits for displaying
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for (int c = 0; c < 192; c++) tft.drawPixel(c, 128 + (255-a)/2, tft.color8to16(tft.color16to8(tft.alphaBlend(a, rainbow(c), 0))));
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}
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// Blend from white to black (4 grey levels - it will draw 4 more with a blue tinge due to lower blue bit count)
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// Blend from black to a primary colour
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for (uint16_t a = 0; a < 255; a++) // Alpha 0 = 100% background, alpha 255 = 100% foreground
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{
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tft.drawFastHLine(192, a, 12, tft.color8to16(tft.color16to8(tft.alphaBlend(a, TFT_BLACK, TFT_WHITE))));
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tft.drawFastHLine(204, a, 12, tft.color8to16(tft.color16to8(tft.alphaBlend(a, TFT_BLACK, TFT_RED))));
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tft.drawFastHLine(216, a, 12, tft.color8to16(tft.color16to8(tft.alphaBlend(a, TFT_BLACK, TFT_GREEN))));
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tft.drawFastHLine(228, a, 12, tft.color8to16(tft.color16to8(tft.alphaBlend(a, TFT_BLACK, TFT_BLUE))));
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}
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delay(4000);
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//*/
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/*
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// 16 bit colours (5 bits red, 6 bits green, 5 bits blue)
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for (int a = 0; a < 256; a+=2) // Alpha 0 = 100% background, alpha 255 = 100% foreground
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{
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for (int c = 0; c < 192; c++) tft.drawPixel(c, a/2, tft.alphaBlend(a, rainbow(c), TFT_CYAN));
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}
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// Blend from full spectrum to cyan
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for (int a = 255; a > 2; a-=2)
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{
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for (int c = 0; c < 192; c++) tft.drawPixel(c, 128 + (255-a)/2, tft.alphaBlend(a, rainbow(c), TFT_YELLOW));
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}
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//*/
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/*
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// Blend other colour transitions for test purposes
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for (uint16_t a = 0; a < 255; a++) // Alpha 0 = 100% background, alpha 255 = 100% foreground
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{
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tft.drawFastHLine(192, a, 12, tft.alphaBlend(a, TFT_WHITE, TFT_WHITE)); // Should show as solid white
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tft.drawFastHLine(204, a, 12, tft.alphaBlend(a, TFT_BLACK, TFT_BLACK)); // Should show as solid black
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tft.drawFastHLine(216, a, 12, tft.alphaBlend(a, TFT_YELLOW, TFT_CYAN)); // Brightness should be fairly even
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tft.drawFastHLine(228, a, 12, tft.alphaBlend(a, TFT_CYAN, TFT_MAGENTA));// Brightness should be fairly even
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}
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delay(4000);
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//*/
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}
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// #########################################################################
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// Return a 16 bit rainbow colour
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// #########################################################################
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unsigned int rainbow(byte value)
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{
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// If 'value' is in the range 0-159 it is converted to a spectrum colour
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// from 0 = red through to 127 = blue to 159 = violet
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// Extending the range to 0-191 adds a further violet to red band
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value = value%192;
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byte red = 0; // Red is the top 5 bits of a 16 bit colour value
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byte green = 0; // Green is the middle 6 bits, but only top 5 bits used here
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byte blue = 0; // Blue is the bottom 5 bits
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byte sector = value >> 5;
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byte amplit = value & 0x1F;
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switch (sector)
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{
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case 0:
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red = 0x1F;
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green = amplit; // Green ramps up
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blue = 0;
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break;
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case 1:
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red = 0x1F - amplit; // Red ramps down
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green = 0x1F;
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blue = 0;
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break;
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case 2:
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red = 0;
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green = 0x1F;
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blue = amplit; // Blue ramps up
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break;
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case 3:
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red = 0;
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green = 0x1F - amplit; // Green ramps down
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blue = 0x1F;
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break;
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case 4:
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red = amplit; // Red ramps up
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green = 0;
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blue = 0x1F;
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break;
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case 5:
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red = 0x1F;
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green = 0;
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blue = 0x1F - amplit; // Blue ramps down
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break;
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}
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return red << 11 | green << 6 | blue;
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}
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