Merge pull request #39 from scottchiefbaker/master

Add an example that uses sprites to update the screen

examples/TFT_eSPI/Fast_Font_Updates/Fast_Font_Updates.ino

@@ -0,0 +1,51 @@
+//////////////////////////////////////////////////////////////////////
+// This example renders millis() to a sprite in the middle of the
+// screen, and then draws over it with a new sprite. This should
+// have the effect of smooth screen updates without any flickering
+// or font tearing.
+//
+// Using this method I can get 100+ FPS on an ESP32 with a size 64
+// font.
+//////////////////////////////////////////////////////////////////////
+
+#include "OpenFontRender.h"
+OpenFontRender ofr;
+
+#include "NotoSans_Bold.h"
+#define TTF_FONT NotoSans_Bold
+
+#include <SPI.h>
+#include <TFT_eSPI.h>
+
+TFT_eSPI tft       = TFT_eSPI();
+TFT_eSprite sprite = TFT_eSprite(&tft);
+
+void setup(void) {
+	tft.begin();
+	tft.setRotation(1);
+	tft.fillScreen(TFT_BLACK);
+
+	ofr.setDrawer(sprite);
+	ofr.loadFont(TTF_FONT, sizeof(TTF_FONT));
+}
+
+void loop() {
+	// Build the sprite and fill it with black
+	void *out = sprite.createSprite(140, 50);
+	if (out == NULL) Serial.println("Could not allocate memory for sprite!");
+	sprite.fillSprite(TFT_BLACK);
+
+	// Set all the font settings and write millis() to the sprite
+	ofr.setFontSize(64);
+	ofr.setCursor(sprite.width() / 2, sprite.height() / 2); // Middle of box
+	ofr.setAlignment(Align::MiddleCenter);
+	ofr.setFontColor(TFT_WHITE, TFT_BLACK);
+	ofr.printf("%d", millis());
+
+	// Calculate the offsets needed to center the sprite box
+	int hcenter = (tft.width()  / 2) - (sprite.width()  / 2);
+	int vcenter = (tft.height() / 2) - (sprite.height() / 2);
+
+	// Push the sprite to the screen
+	sprite.pushSprite(hcenter,vcenter);
+}