Fix STM32H735G build failure with Cargo 1.88+ and display issues

This commit fixes two issues with STM32H735G support:

1. Build failure with Cargo 1.88+
   - Cargo 1.88 (PR rust-lang/cargo#15221) changed linker search path
     ordering to prioritize OUT_DIR paths over external paths
   - This caused ft5336's generic memory.x to take precedence over
     STM32H735G's board-specific memory.x, resulting in undefined
     symbol errors (__e_slint_assets, __s_slint_assets, __si_slint_assets)
   - Fixed by copying board-specific memory.x to OUT_DIR in build.rs,
     ensuring it takes precedence due to build dependency order

2. Display and size optimizations
   - Corrected window size from 320x240 to 480x272 to match actual
     STM32H735G-DK display dimensions
   - Added opt-level="z" to fit within FLASH constraints
   - Improved touch error handling to gracefully handle I2C errors

Tested on STM32H735G-DK hardware with full UI and touch functionality.

Author: task-jp

Cargo.toml

@@ -185,6 +185,7 @@ windows-core = { version = "0.62.0" }
 [profile.release]
 lto = true
 panic = "abort"
+opt-level = "z"  # Optimize for size (needed for STM32H735G FLASH constraints)
 
 [profile.dev]
 panic = "abort"

demos/printerdemo_mcu/ui/printerdemo.slint

@@ -33,8 +33,8 @@ component SideBarIcon inherits Rectangle {
 }
 
 export component MainWindow inherits Window {
-    width: 320px;
-    height: 240px;
+    width: 480px;
+    height: 272px;
     title: "Slint printer demo";
     background: DemoPalette.main-background;
     default-font-family: "Noto Sans";

examples/mcu-board-support/build.rs

@@ -1,9 +1,15 @@
 // Copyright © SixtyFPS GmbH <[email protected]>
 // SPDX-License-Identifier: MIT
 
+use std::env;
+use std::fs;
+use std::path::PathBuf;
+
 fn main() -> std::io::Result<()> {
     #[allow(unused)]
-    let mut board_config_path: Option<std::path::PathBuf> = None;
+    let mut board_config_path: Option<PathBuf> = None;
+    #[allow(unused)]
+    let mut memory_x_source: Option<PathBuf> = None;
 
     cfg_if::cfg_if! {
         if #[cfg(feature = "pico-st7789")] {
@@ -12,6 +18,7 @@ fn main() -> std::io::Result<()> {
             board_config_path = Some([env!("CARGO_MANIFEST_DIR"), "pico2_st7789", "board_config.toml"].iter().collect());
         } else if #[cfg(feature = "stm32h735g")] {
             board_config_path = Some([env!("CARGO_MANIFEST_DIR"), "stm32h735g", "board_config.toml"].iter().collect());
+            memory_x_source = Some([env!("CARGO_MANIFEST_DIR"), "stm32h735g", "memory.x"].iter().collect());
         } else if #[cfg(feature = "stm32u5g9j-dk2")] {
             board_config_path = Some([env!("CARGO_MANIFEST_DIR"), "stm32u5g9j_dk2", "board_config.toml"].iter().collect());
         }
@@ -21,6 +28,19 @@ fn main() -> std::io::Result<()> {
         println!("cargo:BOARD_CONFIG_PATH={}", path.display())
     }
 
+    // Copy memory.x to OUT_DIR and add it to the linker search path.
+    // This ensures the board-specific memory.x takes precedence over
+    // any generic memory.x from dependencies (e.g., ft5336).
+    // Since Cargo 1.88 (PR #15221), OUT_DIR paths are prioritized over external paths,
+    // so we need to place our memory.x in OUT_DIR to ensure it's found first.
+    if let Some(source) = memory_x_source {
+        let out_dir = PathBuf::from(env::var("OUT_DIR").unwrap());
+        let dest = out_dir.join("memory.x");
+        fs::copy(&source, &dest)?;
+        println!("cargo:rustc-link-search={}", out_dir.display());
+        println!("cargo:rerun-if-changed={}", source.display());
+    }
+
     println!("cargo:EMBED_TEXTURES=1");
 
     Ok(())

examples/mcu-board-support/stm32h735g.rs

@@ -353,20 +353,27 @@ impl slint::platform::Platform for StmBackend {
                 });
 
                 // handle touch event
-                let touch = ft5336.detect_touch(&mut inner.touch_i2c).unwrap();
+                let touch = ft5336.detect_touch(&mut inner.touch_i2c).ok();
                 let button = slint::platform::PointerEventButton::Left;
-                let event = if touch > 0 {
-                    let state = ft5336.get_touch(&mut inner.touch_i2c, 1).unwrap();
-                    let position = slint::PhysicalPosition::new(state.y as i32, state.x as i32)
-                        .to_logical(window.scale_factor());
-                    Some(match last_touch.replace(position) {
-                        Some(_) => slint::platform::WindowEvent::PointerMoved { position },
-                        None => slint::platform::WindowEvent::PointerPressed { position, button },
-                    })
+                let event = if let Some(touch_count) = touch {
+                    if touch_count > 0 {
+                        if let Ok(state) = ft5336.get_touch(&mut inner.touch_i2c, 1) {
+                            let position = slint::PhysicalPosition::new(state.y as i32, state.x as i32)
+                                .to_logical(window.scale_factor());
+                            Some(match last_touch.replace(position) {
+                                Some(_) => slint::platform::WindowEvent::PointerMoved { position },
+                                None => slint::platform::WindowEvent::PointerPressed { position, button },
+                            })
+                        } else {
+                            None
+                        }
+                    } else {
+                        last_touch.take().map(|position| {
+                            slint::platform::WindowEvent::PointerReleased { position, button }
+                        })
+                    }
                 } else {
-                    last_touch.take().map(|position| {
-                        slint::platform::WindowEvent::PointerReleased { position, button }
-                    })
+                    None
                 };
 
                 if let Some(event) = event {

examples/mcu-board-support/stm32h735g/board_config.toml

@@ -2,4 +2,4 @@
 # SPDX-License-Identifier: MIT
 
 link_args = ["--nmagic", "-Tlink.x", "-Tdefmt.x"]
-link_search_path = ["."]
+# link_search_path removed: memory.x is now copied to OUT_DIR in build.rs