--- nono/lib/bitmap.cpp	2026/04/29 17:05:12	1.1.1.2
+++ nono/lib/bitmap.cpp	2026/04/29 17:05:15	1.1.1.3
@@ -31,8 +31,8 @@ BitmapBase::~BitmapBase()
 {
 }
 
-// 作成
-void
+// 作成。width_ * height_ が面積を持っていれば true を返す。
+bool
 BitmapBase::Create(int width_, int height_, int depth_)
 {
 	assert(depth_ == 1 || depth_ == 8 || depth_ == 24);
@@ -45,6 +45,8 @@ BitmapBase::Create(int width_, int heigh
 	} else {
 		stride = width * depth_ / 8;
 	}
+
+	return (width > 0 && height > 0);
 }
 
 
@@ -79,10 +81,13 @@ BitmapI1::~BitmapI1()
 void
 BitmapI1::Create(int width_, int height_)
 {
-	inherited::Create(width_, height_, 1);
-
-	owned_buf.reset(new uint8[stride * height]);
-	buf = owned_buf.get();
+	if (inherited::Create(width_, height_, 1)) {
+		owned_buf.reset(new uint8[stride * height]);
+		buf = owned_buf.get();
+	} else {
+		owned_buf.reset();
+		buf = NULL;
+	}
 }
 
 // カラーコード cc で全体を塗りつぶす。
@@ -126,19 +131,24 @@ BitmapI8::~BitmapI8()
 void
 BitmapI8::Create(int width_, int height_)
 {
-	inherited::Create(width_, height_, 8);
-
-	owned_buf.reset(new uint8[stride * height]);
-	buf = owned_buf.get();
+	if (inherited::Create(width_, height_, 8)) {
+		owned_buf.reset(new uint8[stride * height]);
+		buf = owned_buf.get();
+	} else {
+		owned_buf.reset();
+		buf = NULL;
+	}
 }
 
 // 元データを指定して作成
 void
 BitmapI8::Create(const void *buf_, int width_, int height_)
 {
-	inherited::Create(width_, height_, 8);
-
-	buf = static_cast<uint8 *>(const_cast<void *>(buf_));
+	if (inherited::Create(width_, height_, 8)) {
+		buf = static_cast<uint8 *>(const_cast<void *>(buf_));
+	} else {
+		buf = NULL;
+	}
 }
 
 // カラーコード cc で全体を塗りつぶす。
@@ -183,10 +193,13 @@ BitmapRGB::~BitmapRGB()
 void
 BitmapRGB::Create(int width_, int height_)
 {
-	inherited::Create(width_, height_, 24);
-
-	owned_buf.reset(new uint8[stride * height]);
-	buf = owned_buf.get();
+	if (inherited::Create(width_, height_, 24)) {
+		owned_buf.reset(new uint8[stride * height]);
+		buf = owned_buf.get();
+	} else {
+		owned_buf.reset();
+		buf = NULL;
+	}
 }
 
 // 色 c で全体を塗りつぶす。