Fixed bug 1614 - SDL for Android does not implement TextInput API

Andrey Isakov 2012-10-03 08:30:25 PDT

I've found out in the process of porting one OS project to Android/SDL2 that
there is no support for TextInput events/APIs on Android.
So I implemented some kind of initial support of that feature, and at the very
least it seems to work fine with latin chars input with soft and hardware
keyboards on my Moto Milestone2. I've also tried playing around with more
complex IMEs, like japanese, logging the process and it seemed to work too. I'm
not sure since the app itself I am working on does not have support for
non-latin input.

The main point of the patch is to place a fake input view in the region
specified by SDL_SetTextInputRect and create a custom InputConnection for it.
The reason to make it a separate view is to support Android's pan&scan on input
feature properly. For details please refer to
http://android-developers.blogspot.com/2009/04/updating-applications-for-on-screen.html
Even though the manual states that SetTextInputRect is used to determine the
IME variants position, I thought this would be a proper use for this too.

src/video/android/SDL_androidkeyboard.c

@@ -321,6 +321,27 @@ Android_IsScreenKeyboardShown(_THIS, SDL_Window * window)
     return SDL_FALSE;
 }
 
+void
+Android_StartTextInput(_THIS)
+{
+    SDL_VideoData *videodata = (SDL_VideoData *)_this->driverdata;
+    Android_JNI_ShowTextInput(&videodata->textRect);
+}
+
+#define COMMAND_TEXTEDIT_HIDE 3
+void
+Android_StopTextInput(_THIS)
+{
+    Android_JNI_SendMessage(COMMAND_TEXTEDIT_HIDE, 0);
+}
+
+void
+Android_SetTextInputRect(_THIS, SDL_Rect *rect)
+{
+    SDL_VideoData *videodata = (SDL_VideoData *)_this->driverdata;
+    videodata->textRect = *rect;
+}
+
 #endif /* SDL_VIDEO_DRIVER_ANDROID */
 
 /* vi: set ts=4 sw=4 expandtab: */

src/video/android/SDL_androidkeyboard.h

@@ -32,4 +32,8 @@ extern int Android_HideScreenKeyboard(_THIS, SDL_Window * window);
 extern int Android_ToggleScreenKeyboard(_THIS, SDL_Window * window);
 extern SDL_bool Android_IsScreenKeyboardShown(_THIS, SDL_Window * window);
 
+extern void Android_StartTextInput(_THIS);
+extern void Android_StopTextInput(_THIS);
+extern void Android_SetTextInputRect(_THIS, SDL_Rect *rect);
+
 /* vi: set ts=4 sw=4 expandtab: */

src/video/android/SDL_androidvideo.c

@@ -87,17 +87,24 @@ Android_CreateDevice(int devindex)
 {
     printf("Creating video device\n");
     SDL_VideoDevice *device;
+    SDL_VideoData *data;
 
     /* Initialize all variables that we clean on shutdown */
     device = (SDL_VideoDevice *) SDL_calloc(1, sizeof(SDL_VideoDevice));
     if (!device) {
         SDL_OutOfMemory();
-        if (device) {
-            SDL_free(device);
-        }
-        return (0);
+        return NULL;
     }
 
+    data = (SDL_VideoData*) SDL_calloc(1, sizeof(SDL_VideoData));
+    if (!data) {
+        SDL_OutOfMemory();
+        SDL_free(device);
+        return NULL;
+    }
+
+    device->driverdata = data;
+
     /* Set the function pointers */
     device->VideoInit = Android_VideoInit;
     device->VideoQuit = Android_VideoQuit;
@@ -132,6 +139,11 @@ Android_CreateDevice(int devindex)
     device->GetClipboardText = Android_GetClipboardText;
     device->HasClipboardText = Android_HasClipboardText;
 
+    /* Text input */
+    device->StartTextInput = Android_StartTextInput;
+    device->StopTextInput = Android_StopTextInput;
+    device->SetTextInputRect = Android_SetTextInputRect;
+
     return device;
 }
 

src/video/android/SDL_androidvideo.h

@@ -24,6 +24,7 @@
 #define _SDL_androidvideo_h
 
 #include "SDL_mutex.h"
+#include "SDL_rect.h"
 #include "../SDL_sysvideo.h"
 
 /* Called by the JNI layer when the screen changes size or format */
@@ -31,6 +32,11 @@ extern void Android_SetScreenResolution(int width, int height, Uint32 format);
 
 /* Private display data */
 
+typedef struct SDL_VideoData
+{
+    SDL_Rect        textRect;
+} SDL_VideoData;
+
 extern int Android_ScreenWidth;
 extern int Android_ScreenHeight;
 extern Uint32 Android_ScreenFormat;