Starting Emulator Failed to Allocate Memory

What to Try When The Android Emulator Reports A Memory Allocation Error

Occasionally when starting an Android Virtual Device (AVD) or running a project that starts an AVD in Eclipse an allocate memory error is reported. In the Starting Android Emulator dialog a message is seen similar to this one:

Starting emulator for AVD ‘Name of AVD’
Failed to allocate memory: 8
This application has requested the Runtime to terminate it in an unusual way.
Please contact the application’s support team for more information.

For example:

Android Failed To Allocate Memory

This article examines the reason for this error and possible solutions.

Why AVDs Need Large Amount of Memory

The latest Android devices now come with large memories, 1 GiB is now normal, and even larger memories will come in the future. When developing Apps for such devices it is natural to test them on AVDs that have the same specifications as the real world devices. When an AVD is set up using the AVD Manager program it is possible to choose existing device definitions. The Nexus 7 definition sets the RAM to 1024 MiB (1GiB). The RAM setting for the AVD is not all the RAM that the AVD uses. More RAM is required by the system to host and run the emulator code. An AVD given 1024 MiB can use up to 1.5 GiB when it is running. It makes having a high specification machine important when developing Android Apps.

Why AVD Memory Allocation Fails

The Failed to allocate memory:8 error usually occurs because the AVD is configured to have a large amount of RAM (>768 MiB) and the host Operating System (OS) appears not to be in a position to allocate that amount to the AVD (remember it needs to allocate more than specified because of the overhead in running the AVD). The OS may have plenty of memory available but it seems it is not currently in a position to allocate such a large chunk. For example the following screen shot shows the memory status on a Windows 7 64 bit machine with 8GB of memory that displayed the above error when an AVD to emulate a Nexus 7 attempted to start:

Windows resmon Example

This screenshot from the Windows Resource Monitor utility (perfmon.exe /res) shows virtually no free memory, but that is OK because there is plenty of Standby memory, 5.7 GiB. Standby is the memory cache and is available to newly starting programs (Windows will free cached memory when other programs need it). So why did the AVD fail to get a memory allocation? Continue reading

What are DPI, DIP, DP, PPI, SP and Screen Resolutions in Android?

Understanding Android Screen Densities and Terminology

Portrait v LandscapeThis article provides an overview of Android screen densities and the various acronyms that occur when dealing with a device’s screen. Android’s popularity as a mobile device Operating System has resulted in a proliferation of hardware on the market. This has provided great choice for the consumer and forced continuous innovation from the manufacturers. In a few short years there has been rapid innovation in all areas: CPU capabilities, memory size, form factors, keypads, cameras, sensors, batteries, power consumption and screen technologies. The screens have been getting bigger, thinner, sharper, tougher and more responsive to touch. This has forced the Android SDK to move rapidly with the hardware technology (and the hardware to feed upon Android ideas). Explained here is how the variety of screen sizes are handled by the OS, finishing with a summary table of the acronyms covered.

What makes up an Android Screen

Android Coordinate SystemFor those of you new to technology here’s how a device screen works. The screen is made of thousands of small dots called pixels arranged in a grid. The pixels running from left to right are known as the X pixels or X-axis. The pixels running from top to bottom are known as Y pixels or Y-axis. The resolution of the display is the number of pixels in X-axis multipled by the number of pixels in the Y-axis. A 320 by 480 display will have 320 pixels in the X-axis and 480 pixels in the Y-axis, this will also be stated simply as 320×480 (and in this case x is the multiplication, or times, sign and not the X-axis!).

To show an image on the display the color of the pixels are set by a program running on the device. Look at the article How Computer Screens and Printers Show Images for more details on how dots make up an image. Because the Android coordinate system runs left to right and top to bottom then plotting a line from 0,0 to 100,100 results in a line that slopes down from the top left of the screen, compared to one that slopes up from bottom left on a normal maths chart.

To get a idea of the variety of screens seen on Android devices look at the article Example List of Android Device Screen Resolutions and Sizes (which also shows that the various screen resolutions are given names). Continue reading

Text File Edit Component for .NET WinForms Applications

A WinForms .NET Control to Add Text and Source Editing to Windows Applications

Here we show you how to add a lightweight .NET text editor component to a Windows Forms application, the control supports color coding when editing source files (based on the file extension). This component is compatible with version 2.0 of the .NET framework and higher, so it is suitable for use on older versions of Windows, such as Windows XP. The control is called Text File Edit (TFEdit for .NET) and comes as a single DLL (Dynamic Link Library), TextFileEdit.dll. It has several useful properties including turning the display of tabs and spaces on and off, EOL (end-of-line) marker support, showing line numbers and vertical and horizontal rulers. The component is from an Open Source project so all the code is available to change and improve. It comes with a small demonstration project to test it out, here is the component in action in the demo project:

.NET Text Editor

Background

A while back (several years ago) a C# Windows project required a simple text editor to allow users of a program to edit text based files and log files without needing to switch to another application (such as Notepad or Word). The editing capability was a small part of the requirements. At the time the use of the .NET text box did not provide enough functionality, the Rich Text Format control was not suitable, all commercial editors were two complex and added costs to the project. The answer was to extract the text editor portion of a Open Source IDE (Integrated Development Environement) project called SharpDevelop. The SharpDevelop component was called ICSharpCode.TextEditor.dll. This component was refactored to simplify the namespace to TextFileEdit, and a simple test project was written. This was then published on a previous web site where it sat for a few years before the web site was repurposed. With the release of a new version of Visual Studio Express (verison 2012) it was decided to see how well it handled older controls. So the Text File Edit DLL was dusted down and given a go.

Download and Run the Example C# Text Editor

You can download the Text File Edit DLL, source code and a demo test project using the TFEdit.zip file. Extract the contents to a folder on your computer. If you are using Visual Studio Express create a folder, e.g. call it TFEdit, in the Visual Studio Projects directory. Projects is normally in the Visual Studio directory (Visual Studio 2010 or Visual Studio 2012 folders) in My Documents. Open the solution (T_F_E_Solution.sln), the solution was created in Visual Studio 2008 so you will see a conversion report for later editions of Visual Studio. Set the TFETest project as the start-up (select Set as StartUp Project from the context menu). The project should run.

Use the Text File Edit Control in Your Projects

Text File Edit Added to ToolboxThe TextFileEdit.dll is in TextFileEdit\Project\bin\Release. With Visual Studio running start (or open) a Windows Forms Application project. Open the Toolbox (use the View menu if neccessary) and drag and drop the TextFileEdit.dll onto a tab, e.g. the General tab or create a new tab to hold the control. With a WinForm open in design mode drag the TextEditorControl from the Toolbox onto the form. It can then be positioned and properities set.

Text File Edit in Use

The ZIP file that contains the source code has more detailed instructions on adding TFEdit to a project, although it was written sometime ago for Visual Studio 2008.

Text File Edit .NET Control Properties

The TFEdit control supports the following properties:

  • AllowCaretBeyondEOL – When set to “true” the caret (typing cursor) can be moved beyond the end of the actual line. When it goes beyond the last character it is in a screen position and not in any text. Pressing the Return (Enter) key fills the line with spaces up to the point the caret has been moved and creates a new line.
  • BracketMatchingStyle – When set to “After” pairs of brackets, () or [] or {}, are highlighted when the caret moves past them. When set to “Before” the brackets are highlighted as the caret approaches them.
  • ConvertTabsToSpaces – When set to “true and a tab is typed, the tab character is not placed into the text. Instead spaces are placed into the text, the number of spaces being equal to the “TabIndent” property.
  • HideMouseCursor – When set to “true” the mouse cursor his hidden during typing.
  • IndentStyle – When set to “Auto” the text on the next line will start at the same postion as the current text. The same number of tabs and spaces are added to the new line that preceed the current line. When set to “None” no indentation occurs.
  • IsIconBarVisible – Shows a vertical bar on the lef hand side on to which icons can be programmatically placed on a line by line basis.
  • LineViewerStyle – When set to “FullRow” the line that has the focus for typing is highlighted. When set to “None” no highlight is present on the current line.
  • ShowEOLMarkers – When set to “true” a light marker (pilcrow character) is shown to indicate where the end of the line (carriage-return and line-feed character pair) will occur in the text file.
  • ShowHRuler – When set to “true” a “ruler” is drawn at the top of the text, within the control bounds, to give a visual indication of the columns.
  • ShowInvalidLines – When set to “true” the space below the last line will have a marker to show the additional lines that can fit into the area. This markers just indicate the position of additonal lines and are not lines present in the file to be saved.
  • ShowLineNumbers – When set to “true” line numbers appear in a margin at the left of the control within the control boundaries.
  • ShowSpaces – When set to “true” a light dot will indicate a “space” character.
  • ShowTabs – When set to “true” a tab character in the text is indicated by a light right pointing double angle character.
  • ShowVRuler – When set to “true” a vertical line is drawn down the control. It will be positioned at the “text column” indicated by the property “VRulerRow”.The vertical line can be used as a visual guide to determine the length of lines. Sometimes it is necessary to limit the length of lines in a text file for some systems, usually to 80 or 120 characters.
  • TabIndent – This property determines the number of character columns to indent when a tab is pressed or a tab is present in the text.
  • VRulerRow – This property determines the character column in which the vertical ruler line will be displayed.

Issues

When editing source code files the highlighting of paired brackets does not always occur.

Future Releases

There are no plans to release future versions of this control. The source code is available under the LGPL licence for you to make any required changes. The code was taken from an early version of the SharpDevelop IDE. Whilst the text editor in SharpDevelop has changed several times over various SharpDevelop releases TFEdit has not. The current SharpDevelop text editor is a WPF (Windows Presentation Foundation) component called AvalonEdit, it can be loaded into a WPF solution using the Manage NuGet Packages option from the Library Package Manager of the Tools menu, search for AvalonEdit. (To install NuGet select Extensions and Updates from the Tools menu in Visual Studio Express 2012. Select Online in the left hand panel and then NuGet Package Manager, download and install.)

Summary

TFEdit for .NET is a text editor component for WinForms applications. It was used to see if the new 2012 version of Visual Studio Express worked seamlessly with older components. Happily it worked fine for this control. TFEdit is compiled against version 2.0 of the .NET framework so will run on older Windows platforms. In theory it will run across several Operating Systems using Mono but that has not been tried. A compiled DLL, source code and demo program is available in the TFEdit.zip file. It is licensed under LGPL.