Merge pull request #1170 from t-arn/android_scrollcontainer

Implementation of ScrollContainer for Android

Author: freakboy3742

examples/scrollcontainer/scrollcontainer/app.py

@@ -1,39 +1,52 @@
 import toga
-from toga.constants import COLUMN
+from toga.constants import COLUMN, ROW
 from toga.style import Pack
 
 
 class Item(toga.Box):
     def __init__(self, text):
         super().__init__(style=Pack(direction=COLUMN))
 
-        label = toga.Label(text)
-
-        hline = toga.Divider()
-        hline.style.padding_top = 5
-        hline.style.padding_bottom = 5
-
-        self.add(label, hline)
+        row = toga.Box(style=Pack(direction=ROW))
+        for x in range(10):
+            label = toga.Label(text+", "+str(x), style=Pack(padding_right=10))
+            row.add(label)
+        self.add(row)
 
 
 class ScrollContainerApp(toga.App):
-    def startup(self):
+    vscrolling = True
+    hscrolling = False
+    scroller = None
 
+    def startup(self):
         box = toga.Box()
         box.style.direction = COLUMN
         box.style.padding = 10
+        self.scroller = toga.ScrollContainer(horizontal=self.hscrolling, vertical=self.vscrolling)
+        switch_box = toga.Box(style=Pack(direction=ROW))
+        switch_box.add(toga.Switch('vertical scrolling', is_on=self.vscrolling, on_toggle=self.handle_vscrolling))
+        switch_box.add(toga.Switch('horizontal scrolling', is_on=self.hscrolling, on_toggle=self.handle_hscrolling))
+        box.add(switch_box)
 
         for x in range(100):
             label_text = 'Label {}'.format(x)
             box.add(Item(label_text))
 
-        scroller = toga.ScrollContainer(horizontal=False)
-        scroller.content = box
+        self.scroller.content = box
 
-        self.main_window = toga.MainWindow(self.name)
-        self.main_window.content = scroller
+        self.main_window = toga.MainWindow(self.name, size=(400, 700))
+        self.main_window.content = self.scroller
         self.main_window.show()
 
+    def handle_hscrolling(self, widget):
+        self.hscrolling = widget.is_on
+        self.scroller.horizontal = self.hscrolling
+
+    def handle_vscrolling(self, widget):
+        self.vscrolling = widget.is_on
+        self.scroller.vertical = self.vscrolling
+
 
 def main():
     return ScrollContainerApp('ScrollContainer', 'org.beeware.widgets.scrollcontainer')

src/android/toga_android/factory.py

@@ -12,6 +12,7 @@
 from .widgets.multilinetextinput import MultilineTextInput
 from .widgets.passwordinput import PasswordInput
 from .widgets.selection import Selection
+from .widgets.scrollcontainer import ScrollContainer
 from .widgets.slider import Slider
 from .widgets.switch import Switch
 from .widgets.textinput import TextInput
@@ -38,6 +39,7 @@ def not_implemented(feature):
     "PasswordInput",
     "Selection",
     "Slider",
+    "ScrollContainer",
     "Switch",
     "TextInput",
     "WebView",

src/android/toga_android/libs/android.py

@@ -0,0 +1,4 @@
+from rubicon.java import JavaClass, JavaInterface
+
+MotionEvent = JavaClass("android/view/MotionEvent")
+View__OnTouchListener = JavaInterface("android/view/View$OnTouchListener")

src/android/toga_android/libs/android_widgets.py

@@ -8,6 +8,7 @@
 DialogInterface__OnClickListener = JavaInterface("android/content/DialogInterface$OnClickListener")
 EditText = JavaClass("android/widget/EditText")
 Gravity = JavaClass("android/view/Gravity")
+HorizontalScrollView = JavaClass("android/widget/HorizontalScrollView")
 ImageView = JavaClass("android/widget/ImageView")
 ImageView__ScaleType = JavaClass("android/widget/ImageView$ScaleType")
 InputType = JavaClass("android/text/InputType")

src/android/toga_android/widgets/scrollcontainer.py

@@ -0,0 +1,79 @@
+from travertino.size import at_least
+
+from ..libs import android_widgets, android
+from .base import Widget
+from toga_android.window import AndroidViewport
+
+
+class TogaOnTouchListener(android.View__OnTouchListener):
+    is_scrolling_enabled = True
+
+    def __init__(self):
+        super().__init__()
+
+    def onTouch(self, view, motion_event):
+        if self.is_scrolling_enabled:
+            return view.onTouchEvent(motion_event)
+        else:
+            return True
+
+
+class ScrollContainer(Widget):
+    vScrollListener = None
+    hScrollView = None
+    hScrollListener = None
+
+    def create(self):
+        vScrollView = android_widgets.ScrollView(self._native_activity)
+        vScrollView_layout_params = android_widgets.LinearLayout__LayoutParams(
+            android_widgets.LinearLayout__LayoutParams.MATCH_PARENT,
+            android_widgets.LinearLayout__LayoutParams.MATCH_PARENT
+        )
+        vScrollView_layout_params.gravity = android_widgets.Gravity.TOP
+        vScrollView.setLayoutParams(vScrollView_layout_params)
+        self.vScrollListener = TogaOnTouchListener()
+        self.vScrollListener.is_scrolling_enabled = self.interface.vertical
+        vScrollView.setOnTouchListener(self.vScrollListener)
+        self.native = vScrollView
+        self.hScrollView = android_widgets.HorizontalScrollView(self._native_activity)
+        hScrollView_layout_params = android_widgets.LinearLayout__LayoutParams(
+            android_widgets.LinearLayout__LayoutParams.MATCH_PARENT,
+            android_widgets.LinearLayout__LayoutParams.MATCH_PARENT
+        )
+        hScrollView_layout_params.gravity = android_widgets.Gravity.LEFT
+        self.hScrollListener = TogaOnTouchListener()
+        self.hScrollListener.is_scrolling_enabled = self.interface.horizontal
+        self.hScrollView.setOnTouchListener(self.hScrollListener)
+        vScrollView.addView(self.hScrollView, hScrollView_layout_params)
+        if self.interface.content is not None:
+            self.set_content(self.interface.content)
+
+    def set_content(self, widget):
+        widget.viewport = AndroidViewport(widget.native)
+        content_view_params = android_widgets.LinearLayout__LayoutParams(
+            android_widgets.LinearLayout__LayoutParams.MATCH_PARENT,
+            android_widgets.LinearLayout__LayoutParams.MATCH_PARENT
+        )
+        widget_parent = widget.native.getParent()
+        if widget_parent is not None:
+            widget_parent.removeView(widget.native)
+        self.hScrollView.addView(widget.native, content_view_params)
+        for child in widget.interface.children:
+            child._impl.container = widget
+
+    def set_vertical(self, value):
+        self.vScrollListener.is_scrolling_enabled = value
+
+    def set_horizontal(self, value):
+        self.hScrollListener.is_scrolling_enabled = value
+
+    def rehint(self):
+        # Android can crash when rendering some widgets until they have their layout params set. Guard for that case.
+        if self.native.getLayoutParams() is None:
+            return
+        self.native.measure(
+            android_widgets.View__MeasureSpec.UNSPECIFIED,
+            android_widgets.View__MeasureSpec.UNSPECIFIED,
+        )
+        self.interface.intrinsic.width = at_least(self.native.getMeasuredWidth())
+        self.interface.intrinsic.height = self.native.getMeasuredHeight()