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Display — Utilities

M5GFX source: lgfx/v1/LGFXBase.hpp
Back to: Display overview

Screen control, QR code generation, progress bar, state save/restore, and drawing sessions.

Screen Control

fillScreen()

void fillScreen();                        // Fill with base color
void fillScreen(uint16_t color);          // Fill with specified color

Fills the entire screen with a solid color.

M5Cardputer.Display.fillScreen(TFT_BLACK);

// Clear to default background
M5Cardputer.Display.setBaseColor(TFT_NAVY);
M5Cardputer.Display.fillScreen();

setBrightness() / getBrightness()

void setBrightness(uint8_t brightness);   // 0–255 (0=off, 255=max)
uint8_t getBrightness() const;

Controls the LCD backlight.

void setup() {
    M5Cardputer.begin();
    M5Cardputer.Display.setBrightness(128);  // 50%
}

void onDimTimer() {
    // Fade to 20% after idle
    M5Cardputer.Display.setBrightness(51);
}

setRotation() / getRotation()

void setRotation(uint8_t rotation);   // 0–3
uint8_t getRotation() const;

Rotates the screen coordinate system.

Value Orientation Resolution
0 Portrait 240 × 320
1 Landscape 320 × 240
2 Portrait (inverted) 240 × 320
3 Landscape (inverted) 320 × 240 
M5Cardputer.Display.setRotation(1);  // Default landscape
M5Cardputer.Display.printf("W=%d H=%d\n",
    M5Cardputer.Display.width(),
    M5Cardputer.Display.height());   // 320 x 240

width() / height()

int32_t width() const;
int32_t height() const;

Returns the current display dimensions, post-rotation.

int32_t centerX = M5Cardputer.Display.width() / 2;
int32_t centerY = M5Cardputer.Display.height() / 2;
M5Cardputer.Display.drawCircle(centerX, centerY, 30, TFT_RED);

sleep() / wakeup()

void sleep();    // Turn off display
void wakeup();   // Wake display from sleep

Power management for the LCD.

// Dim after inactivity
if (millis() - lastActivity > 30000) {
    M5Cardputer.Display.sleep();
}

// Wake on button press
if (M5Cardputer.BtnA.wasPressed()) {
    M5Cardputer.Display.wakeup();
    lastActivity = millis();
}

invertDisplay()

void invertDisplay(bool invert);
bool getInvert() const;

Inverts all pixels on screen (useful for some panel configurations).

M5Cardputer.Display.invertDisplay(true);
delay(500);
M5Cardputer.Display.invertDisplay(false);

QR Code

qrcode()

void qrcode(const char* string, int32_t x = -1, int32_t y = -1,
            int32_t width = -1, uint8_t version = 1);

Draws a QR code directly on the display.

Parameter Type Default Description
string const char* — Data to encode
x, y int32_t -1 Position (-1 = centered)
width int32_t -1 Size (-1 = maximum fit)
version uint8_t 1 QR version (1–40, determines data capacity) 
// Auto-centered
M5Cardputer.Display.qrcode("https://m5stack.com", -1, -1, -1);

// Custom position and size
M5Cardputer.Display.qrcode("hello123", 10, 10, 100);

Progress Bar

progressBar()

void progressBar(int x, int y, int w, int h, uint8_t val);

M5GFX-specific convenience widget. Draws a simple progress bar.

Parameter Type Description
x, y int Top-left
w, h int Width and height
val uint8_t Progress value 0–100 
void loadingScreen() {
    M5Cardputer.Display.fillScreen(TFT_BLACK);
    M5Cardputer.Display.setTextColor(TFT_WHITE);
    M5Cardputer.Display.drawString("Loading...", 10, 10);

    for (int i = 0; i <= 100; i += 10) {
        M5Cardputer.Display.progressBar(40, 80, 240, 20, i);
        delay(200);
    }
}

State Save / Restore

pushState() / popState()

void pushState();   // Save font, text style, cursor, colors
void popState();    // Restore saved state

LIFO stack for graphics state. Use when temporarily changing font/size/color inside a function.

void drawHeader(const char* title) {
    M5Cardputer.Display.pushState();
    M5Cardputer.Display.setTextSize(2);
    M5Cardputer.Display.setTextColor(TFT_WHITE, TFT_NAVY);
    M5Cardputer.Display.drawCenterString(title, 160, 15);
    M5Cardputer.Display.popState();   // Original settings restored
}

void drawBodyLine(const char* text) {
    M5Cardputer.Display.println(text);  // Uses original settings
}

Write Sessions

startWrite() / endWrite()

void startWrite();   // Begin a drawing session
void endWrite();     // End and flush

Wraps multiple drawing operations in a single SPI transaction for better performance.

M5Cardputer.Display.startWrite();
for (int i = 0; i < 100; i++) {
    int x = random(320);
    int y = random(240);
    M5Cardputer.Display.drawPixel(x, y, TFT_WHITE);
}
M5Cardputer.Display.endWrite();