minui: Refactor GRSurfaceFbdev.

- Adds Create() that returns a GRSurfaceFbdev instance.
- Moves away from using the copy ctor (precisely assignment operator) of
  GRSurfaceFbdev.
- Moves the GRSurfaceFbdev deallocation code into GRSurfaceFbdev's dtor.
- Manages MinuiBackendFbdev::gr_framebuffer with std::unique_ptr.

Test: mmma -j bootable/recovery
Test: `Run graphics test` on taimen.
Change-Id: I8e67cda7bc3a2feec0790124d035caa36fb58a89

minui/graphics_fbdev.cpp

@@ -26,21 +26,27 @@
 #include <sys/types.h>
 #include <unistd.h>
 
+#include <memory>
+
 #include "minui/minui.h"
 
-MinuiBackendFbdev::MinuiBackendFbdev() : gr_draw(nullptr), fb_fd(-1) {}
+std::unique_ptr<GRSurfaceFbdev> GRSurfaceFbdev::Create(int width, int height, int row_bytes,
+                                                       int pixel_bytes) {
+  // Cannot use std::make_unique to access non-public ctor.
+  return std::unique_ptr<GRSurfaceFbdev>(new GRSurfaceFbdev(width, height, row_bytes, pixel_bytes));
+}
 
 void MinuiBackendFbdev::Blank(bool blank) {
   int ret = ioctl(fb_fd, FBIOBLANK, blank ? FB_BLANK_POWERDOWN : FB_BLANK_UNBLANK);
   if (ret < 0) perror("ioctl(): blank");
 }
 
-void MinuiBackendFbdev::SetDisplayedFramebuffer(unsigned n) {
+void MinuiBackendFbdev::SetDisplayedFramebuffer(size_t n) {
   if (n > 1 || !double_buffered) return;
 
-  vi.yres_virtual = gr_framebuffer[0].height * 2;
-  vi.yoffset = n * gr_framebuffer[0].height;
-  vi.bits_per_pixel = gr_framebuffer[0].pixel_bytes * 8;
+  vi.yres_virtual = gr_framebuffer[0]->height * 2;
+  vi.yoffset = n * gr_framebuffer[0]->height;
+  vi.bits_per_pixel = gr_framebuffer[0]->pixel_bytes * 8;
   if (ioctl(fb_fd, FBIOPUT_VSCREENINFO, &vi) < 0) {
     perror("active fb swap failed");
   }
@@ -96,35 +102,31 @@ GRSurface* MinuiBackendFbdev::Init() {
 
   memset(bits, 0, fi.smem_len);
 
-  gr_framebuffer[0].width = vi.xres;
-  gr_framebuffer[0].height = vi.yres;
-  gr_framebuffer[0].row_bytes = fi.line_length;
-  gr_framebuffer[0].pixel_bytes = vi.bits_per_pixel / 8;
-  gr_framebuffer[0].buffer_ = static_cast<uint8_t*>(bits);
-  memset(gr_framebuffer[0].buffer_, 0, gr_framebuffer[0].height * gr_framebuffer[0].row_bytes);
+  gr_framebuffer[0] =
+      GRSurfaceFbdev::Create(vi.xres, vi.yres, fi.line_length, vi.bits_per_pixel / 8);
+  gr_framebuffer[0]->buffer_ = static_cast<uint8_t*>(bits);
+  memset(gr_framebuffer[0]->buffer_, 0, gr_framebuffer[0]->height * gr_framebuffer[0]->row_bytes);
+
+  gr_framebuffer[1] =
+      GRSurfaceFbdev::Create(gr_framebuffer[0]->width, gr_framebuffer[0]->height,
+                             gr_framebuffer[0]->row_bytes, gr_framebuffer[0]->pixel_bytes);
 
   /* check if we can use double buffering */
   if (vi.yres * fi.line_length * 2 <= fi.smem_len) {
     double_buffered = true;
 
-    gr_framebuffer[1] = gr_framebuffer[0];
-    gr_framebuffer[1].buffer_ =
-        gr_framebuffer[0].buffer_ + gr_framebuffer[0].height * gr_framebuffer[0].row_bytes;
-
-    gr_draw = gr_framebuffer + 1;
-
+    gr_framebuffer[1]->buffer_ =
+        gr_framebuffer[0]->buffer_ + gr_framebuffer[0]->height * gr_framebuffer[0]->row_bytes;
   } else {
     double_buffered = false;
 
-    // Without double-buffering, we allocate RAM for a buffer to
-    // draw in, and then "flipping" the buffer consists of a
-    // memcpy from the buffer we allocated to the framebuffer.
-
-    gr_draw = new GRSurfaceFbdev;
-    *gr_draw = gr_framebuffer[0];
-    gr_draw->buffer_ = new uint8_t[gr_draw->height * gr_draw->row_bytes];
+    // Without double-buffering, we allocate RAM for a buffer to draw in, and then "flipping" the
+    // buffer consists of a memcpy from the buffer we allocated to the framebuffer.
+    memory_buffer.resize(gr_framebuffer[1]->height * gr_framebuffer[1]->row_bytes);
+    gr_framebuffer[1]->buffer_ = memory_buffer.data();
   }
 
+  gr_draw = gr_framebuffer[1].get();
   memset(gr_draw->buffer_, 0, gr_draw->height * gr_draw->row_bytes);
   fb_fd = fd;
   SetDisplayedFramebuffer(0);
@@ -139,25 +141,19 @@ GRSurface* MinuiBackendFbdev::Init() {
 
 GRSurface* MinuiBackendFbdev::Flip() {
   if (double_buffered) {
-    // Change gr_draw to point to the buffer currently displayed,
-    // then flip the driver so we're displaying the other buffer
-    // instead.
-    gr_draw = gr_framebuffer + displayed_buffer;
+    // Change gr_draw to point to the buffer currently displayed, then flip the driver so we're
+    // displaying the other buffer instead.
+    gr_draw = gr_framebuffer[displayed_buffer].get();
     SetDisplayedFramebuffer(1 - displayed_buffer);
   } else {
     // Copy from the in-memory surface to the framebuffer.
-    memcpy(gr_framebuffer[0].buffer_, gr_draw->buffer_, gr_draw->height * gr_draw->row_bytes);
+    memcpy(gr_framebuffer[0]->buffer_, gr_draw->buffer_, gr_draw->height * gr_draw->row_bytes);
   }
   return gr_draw;
 }
 
 MinuiBackendFbdev::~MinuiBackendFbdev() {
-  close(fb_fd);
-  fb_fd = -1;
-
-  if (!double_buffered && gr_draw) {
-    delete[] gr_draw->buffer_;
-    delete gr_draw;
+  if (fb_fd != -1) {
+    close(fb_fd);
   }
-  gr_draw = nullptr;
 }

minui/graphics_fbdev.h

@@ -19,37 +19,50 @@
 #include <linux/fb.h>
 #include <stdint.h>
 
+#include <memory>
+#include <vector>
+
 #include "graphics.h"
 #include "minui/minui.h"
 
 class GRSurfaceFbdev : public GRSurface {
  public:
+  // Creates and returns a GRSurfaceFbdev instance, or nullptr on error.
+  static std::unique_ptr<GRSurfaceFbdev> Create(int width, int height, int row_bytes,
+                                                int pixel_bytes);
+
   uint8_t* data() override {
     return buffer_;
   }
 
+ protected:
+  using GRSurface::GRSurface;
+
  private:
   friend class MinuiBackendFbdev;
 
   // Points to the start of the buffer: either the mmap'd framebuffer or one allocated in-memory.
-  uint8_t* buffer_;
+  uint8_t* buffer_{ nullptr };
 };
 
 class MinuiBackendFbdev : public MinuiBackend {
  public:
+  MinuiBackendFbdev() = default;
+  ~MinuiBackendFbdev() override;
+
   GRSurface* Init() override;
   GRSurface* Flip() override;
   void Blank(bool) override;
-  ~MinuiBackendFbdev() override;
-  MinuiBackendFbdev();
 
  private:
-  void SetDisplayedFramebuffer(unsigned n);
+  void SetDisplayedFramebuffer(size_t n);
 
-  GRSurfaceFbdev gr_framebuffer[2];
+  std::unique_ptr<GRSurfaceFbdev> gr_framebuffer[2];
+  // Points to the current surface (i.e. one of the two gr_framebuffer's).
+  GRSurfaceFbdev* gr_draw{ nullptr };
   bool double_buffered;
-  GRSurfaceFbdev* gr_draw;
-  int displayed_buffer;
+  std::vector<uint8_t> memory_buffer;
+  size_t displayed_buffer{ 0 };
   fb_var_screeninfo vi;
-  int fb_fd;
+  int fb_fd{ -1 };
 };