Merge pull request #28 from MLXXXp/widget_background_demo

Example sketch to demonstrate use of widget setValue() optional second argument

examples/MicroViewWidgetBackground/MicroViewWidgetBackground.ino

@@ -0,0 +1,90 @@
+/*
+  MicroView Arduino Library
+  Copyright (C) 2015 GeekAmmo
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+/*
+  An example of using the optional second argument of the widget
+  setVal() function to update a widget without drawing the changes
+  to the screen buffer.
+
+  This, along with the widget reDraw() function, allows widgets to be
+  maintained in the "background" while other things are being displayed.
+
+  In this example,
+  a guage and a slider are both continually updated with the same
+  incrementing value. The widgets are alternately switched between the
+  "background" and being displayed, at random intervals.
+*/
+
+#include <MicroView.h>
+
+const int highVal = 100; // high value for widget range
+
+int wValue = 0; // value for widgets
+
+MicroViewWidget *guage1, *slider1;
+boolean guage1On, slider1On; // true if widget is being displayed
+
+void setup() {
+  uView.begin();
+
+  guage1 = new MicroViewGauge(32, 20, 0, highVal);
+  guage1On = false; // begin with guage1 off screen
+  uView.clear(PAGE);
+  
+  slider1 = new MicroViewSlider(8, 16, 0, highVal);
+  slider1On = true; // begin with slider1 on screen
+
+  // Init the random number generator using an
+  // unconnected analog pin.
+  randomSeed(analogRead(A0));
+}
+
+void loop() {
+  // Display a widget for a random number of value increments
+  for (int c = random(5, 16); c > 0; c--) {
+    uView.display();
+    delay(500);
+
+    wValue++;
+    if (wValue > highVal) {
+      wValue = 0;
+    }
+
+    // If the second setValue() argument is false, then
+    // the display buffer is not updated.
+    //
+    // In a practical application, the widgets would be set with
+    // the values that are being monitored.
+    guage1->setValue(wValue, guage1On);
+    slider1->setValue(wValue, slider1On);
+  }
+
+  // Switch which widget is being displayed
+  uView.clear(PAGE);
+
+  guage1On = !guage1On;
+  slider1On = !slider1On;
+
+  if (guage1On) {
+    guage1->reDraw();
+  }
+
+  if (slider1On) {
+    slider1->reDraw();
+  }
+}